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ra2jim 08-23-2016 06:11 PM

Mileage for 2001 RoadTrek170
14.7 mpg
one way, 264 miles over 4500-ft elevation rise
Dodge 2500 chassis 5.2L V8 (only 12,000 miles!)
2 people, moderate load
clear weather, 10-15 mph crosswind half the time

AZ ADVenturist 08-24-2016 03:13 PM

That's what we averaged w/ our Chev 190Versitile 5.7 (350ci). Sometimes worse. Now getting 16.5 - 17mpg with our '13 190 R/T. 6liter motor. Great!

ra2jim 08-24-2016 05:03 PM

That's great AZ - larger engine longer rig than mine but better mileage! I guess that's the price for driving older models. I haven't filled back up the tank yet so I'm curious to know my return trip mileage since it was generally mostly down hill.

My first goal is to reach above 15 mpg. That's only 5% more. Even so, I'm wondering if that can be achieved by lessening weight like remove original TV/vcr, replace all kitchen stuff with lightweight equivalents, replace some cabinets, side door passenger seat box, large overhead drawer above front cab, lighter bike rack, water tanks to acceptable minimum, buy food at destination, etc. That's probably not even close to 5% of gross weight - maybe not enough to put a dent in the mpg. Oh yeah, maybe the wife & I can lose weight...

I know that keeping the engine tip top shape is important. I'm wondering if better octane gas or using additives does anything.

Achieving that balance of economy and comfort is not easy - but the challenge is kind of fun!

mkguitar 08-24-2016 05:23 PM

often a larger motor and more torque uses less revs- less fuel.

my 2001 GMC pick up has the 4.8 vortec and is usually empty and gets about 20 MPG.

when loaded the mpg drops quickly- on hills the tranny will hunt between 3rd and OD- this up and down as it tries to get best performance is a pain, and many of us with that motor shift to stay in 3rd on hills.
My Pal has same truck with the 5.3...his is actually nicer to drive on hills and his mpg avg is better than mine ( compared over the 15 years...!)

the 6.0 Vortec in my 06 PW is better sized for the weight of the rv and we get about 16 mpg at 65 mph- on flat with no ethanol gas we have seen 18. The larger motor has more torque and doesn;t rev as high to get moving from a stop and doesn;t need to downshift as much/often on hills.

so bigger isn;t always thirstier

right at 99/2000 is when the big 3 motors got alot better for efi controls and mpg.


AZ ADVenturist 08-24-2016 10:50 PM

Mike, have you found a 'tuner' in Phx area? I've been told that a properly turned & well setup LS motor can achieve low 20smpg. Although maybe not cost effective in a limited use "lumber-ing wagon" as a class B.

Jim - I'm not sure higher octane fuel or "snake oil " additives are worth the very low % increase of mpg.
Regards, Ric.
P.S. I love my 6liter w/ 6spd transmission. No hunting between gears.

mkguitar 08-25-2016 04:57 PM

I don't think the MPG and "performance" go together with out major changes such as defeating the emission controls ( and Maricopa County puts my B on the rollers due to the GVWR).
Possible that gains may be seen with another type exhaust, but the pay off is years down the road- and for our driving i don't wanna noisy exhaust

I have some ASE training- but am more a hobbiest.

look at it this way- the manufacturers have a real reason to up MPG ( CAFE standards)- and power output ( the market), so they do within reason ( cost).
We love our bulletproof 6 liter vortecs- they are really efficient- I have some older cars with 7 and 8.2 liter motors which provide much less power , use much more fuel, spew more CO and HC and take more fiddling

as far as octane- the vehicle is designed for a certain octane fuel- below that the ECM will have to retard spark timing to prevent detonation/pinging- retarded timing will give poorer MPG.
above the spec'd rating, higher octane does no good.

So best economy- pump gas price and best MPG is usually right in your manual. Keep that in mind in Colorado where 85 abounds...go for the midgrade or blend your own...1/2 85 and 1/2 89 = 87

The iphone gasbuddy app helps me plan fuel stops by location, price and grade

basic to economy are clean air filter, correct spark plugs, tires and psi and weight...don;t roll with full water tanks if you don;t need to


AZ ADVenturist 08-25-2016 08:05 PM

Agreed. Well said!

ra2jim 08-25-2016 10:26 PM

Some good input here - thanks guys. I wanted to add that I was drafting behind 18-wheelers about half the time but just got a little bored!

Anyway, I think this van is new enough to have one of those odbII ports - if true, I'm thinking of getting one of those readers to get some stats. Any opinion on what data could be most helpful? I understand there are phone apps that will display them live. Any of you use this?

My other car is a ford escape hybrid which has a decent set of data showing up on the dashboard. I miss that on the RT.

Davydd 08-25-2016 11:10 PM

How close do you have to be to draft behind an 18 wheeler? I find when I am behind an 18 wheeler at an appropriately safe distance that I get a lot of buffeting. So I always drop back further or I pass them.

mkguitar 08-25-2016 11:12 PM

scan gauge ii is about $130

drafting is tricky- in order to be close enough to take can;t see- and if you are far back enough to see, you are in their air which will reduce you mpg.

you will notice that when passing a truck, as you approach there is dirty air buffeting and resistance- once you get past the trailer wheels you are in clean air and can get by more easily.

2.) a tire will kill you, never sit your vehicle next to the truck's tires on the road- get by quick


Davydd 08-26-2016 12:16 AM

In drafting I would assume then if you can't see then you most likely could not stop in time either.

AZ ADVenturist 08-26-2016 01:21 AM

We have found one way to save a few 10ths mpg is to turn off AC when going up hill. Turn on again on more level ground, which is rare in the West.
So it is a good idea to plan your route so as to always be going Down hill!
Especially in the Rocky Mountains...
Of course YMMV!

booster 08-26-2016 01:32 AM

We used to be very careful about mileage. Drive slowly, limit weight of water, etc. As we got the handling of the van better, it got very easy to drive at higher speeds, and when we are booking time to get somewhere or home, we go much faster than we used to, usually averaging 67mph, even in nasty winds. We can afford a little more gas to cover 800 miles instead of 600, if it gets us where we want to be and is not any more effort. Of course, when we are touring nice areas we are going slower, but don't make an effort to wring out every 1/10th of mileage, it is just not worth the hassle.

These days, the only time we do a careful mileage run is to check the baseline mileage to make sure the van is running properly. Not sweating the gas mileage all the time makes the travel way more enjoyable for use.

As odd as it may sound, we get the best mileage in rolling hills. Even better than on flat constant load driving. Surprisingly, the physics actually backs up the actual in this case. There was a thread on this here a number of years ago.

ra2jim 08-26-2016 01:37 AM

Davydd, you're right it is dangerous, will probably do it from farther if that in fact does anything at all. I would say I was 4 car lengths behind at 60mph. I heard somewhere before that race cars at 2 feet get more than 25% more, then it slides from there right up to about 100 ft. I guess it was also the only place to be driving slower than the rest. Never in my driving life had so many bus RVs pass me up !!!

On hills I usually find the sweet spot watching the tachometer & listening to engine sound. It's a bit tricky but I've only driven this 3 times.

AZ, wife & I never turn AC unless it's over 100 outside (always trying to escape San Francisco's foggy summers). I use to drive an old Datsun B210 way back and could never figure out why it overheated so used to turn heater on especially on hill climbs-just to get the temp down.

Mike, my brother in law drives an 18-whlr for a living and he has lots of don't-do-this advice....

ra2jim 08-29-2016 07:26 PM

Just an update on the return trip mileage. As expected the mostly downhill run yielded 15.72 mpg - a little over 6% better. So I'll set my average at 15.2 mpg.
Next goal is 16. The plan is get engine tune-up, change fluids (is synthetic oil really better?), follow weight shedding plan, drive/accelerate slower....and pick a windless day!

mkguitar 08-29-2016 07:41 PM

synthetic oil works great in motors designed for it- with close tolerances.

I have used synthetic 20w50 or 10w-40 since new in my 2001 GMC 4.8 pick up
I have 165k with no problems. Usually mobil 1- $23 at walmart. I change every 3000 miles ( overkill but I live in a high heat, dusty area)

The 20 will be thick enough to move quickly to lube the motor on start up, the 50 will resist break down when it is hot...I may use 10w-40 in the winter if I happen to have an oil change coincide with our 2 weeks of winter.

on most chevs, the oil is easily changed just by laying on the ground and reaching in from the side. no need to jack it up


Bruceper 08-29-2016 10:45 PM


Originally Posted by mkguitar (Post 47566)
synthetic oil works great in all engines.

I fixed that for you.

mkguitar 08-30-2016 03:46 AM

synthetic doesn;t work well in older motors with loose tolerances- in many cases it will seep out through paper gaskets used between rough castings ( modern motors will use a plasticized surface on the steel gasket to seal nice tight joints

on a worn motor with deposits, synthetic may lift this crud and start it moving through the motor where it can crud up fine passages in the lifters or bearing journals.

as much as I'd like to, I can;t use synthetic in my old 50's, 60's and 70's motors for those reasons.
even older motors rebuilt and machined just don;t have the quality of metals used to resist seeping


Bruceper 08-30-2016 11:29 AM

Synthetic oil is no longer alcohol based. The seepage you are talking about is a decades old issue that is now a myth about synthetic oils, it just doesn't happen anymore. I use Mobil 1 in all of my vehicles including an original, un-rebuilt 1972 360 V8 in my 1982 Dodge shortbox.

The only thing it may/will do is release scale and deposits which can be dealt with by a secondary oil change.

booster 08-30-2016 01:45 PM

I think the synthetic oil arguments will go on forever :partyman:

I am neither a hater or a great lover of synthetics, so no huge bias, I hope.

I use both, and have success with both. 1992 Escort ran for 18.5 years, 210K miles, of ugly Minnesota commuting. I used Castrol dino oil in it, and when it went to the junk yard it would still go 10K miles without adding oil and never leaked. We went to synthetic in our small engine lawn tractor engine and hydro transmission and they run noticeably cooler.

I also have had issues with synthetic. Several older flat hydraulic lifter engines I have been around would have tappet noise on synthetic. I have seen the leaking issue, and it is not just in engines. I changed my 96 Buick Roadmaster 4L60E to the Dexron VI fluid and got a leak in a cooling line within weeks. Pan gaskets on both trans and engines seem to have issues if they are not the new reusable, inserted spacer, silicone type like we have on the 07 Chevy 6.0 engine. I quit using the regular gaskets on the trans pans a long time ago and use Right Stuff with no gasket, as it is the only way I can get rid of the leaks.

Synthetics have also morphed due to some rule changes in what can be called full synthetic, it appears. Nearly all the major brands that are called full synthetic are now group III oils, or mixes of III and IV, I have been told. Those would not have been able to be labeled full synthetic a few years ago. Again second hand information, but Amsoil and Royal Purple are both said to still be 100% group IV oils. Redline is said to be nearly all group V oil which is a different chemical group that is very slippery and tolerates substantially higher heat.

I did read some information a while ago, that was written by a chemist IIRC. I found it very interesting. His claim was that group II and III oils were pretty much neutral in affecting seal hardening and leaking (this is for rubber seals, not the composition types). Group IV oils were said to soften the rubber seals some, which could help some rotating seals a bit, or make them leak. Stationary seals could start to leak. Group V oils were said to slightly harden rubber seals, which could make the wear faster and leak if rotating, and have less affect on stationary ones. He also claimed that a mix of the IV and V would be the best, but I forget the ratio, saying it would get back to neutral on the sealing, but give a lot of the extra temp and lubrication of the group V to the stability of group IV. He even thought the Redline was putting some group IV into their oils lately, but had no data to prove it.

What we use;

07 Roadtrek (6.0, 4L80E) : Mobil1 5-30 in the engine, Dexron VI in the trans. Amsoil Dexron IV in the power steering hydoboost system (definite improvement), either Redline or Amsoil extreme duty rear differential oil.

09 Honda CRV: All Honda fluids except the engine oil which is Mobil1 5-30. Hondas seem to be very picky on their fluids, and I have seen just too many messed up with non Honda products in the trans and power steering.

96 Buick Roadmaster: (5.7 LT1, 4L60E) (130K miles) Castrol 5-30 oil, Dexron VI in trans, Redline or Amsoil rear gear oil, Redline power steering fluid.

John Deere lawn tractor (17hp air cooled Kawasaki): Redline 10-40 motorcycle oil, Redline 20-50 motorcycle oil in the hydo trans.

Of course, everyone has their own opinions on this topic, and always will!

ra2jim 08-31-2016 01:53 AM

Gentlemen, your opinions/knowledge of oil is nothing short of amazing! Ultimately I'm still shooting for better mileage, and were I to choose, I would put money on less weight vs changing to synthetic least for now.
Thank you.
This Labor Day weekend, I'm crazy enough to agree with my wife to do a short 100 mile drive (along with the rest of the country) to a nearby state park....should be fun driving bumper to bumper..

Have a fun holiday guys!

AZ ADVenturist 09-01-2016 02:37 AM

Just watch out for the other guy /gals. No sight seeing while driving.
I learned the hard way driving "coast hiway " in Oregon in July.
It was the other guys fault - honest! His insurance paid! !

BBQ 09-04-2016 05:18 PM

booster 09-04-2016 08:17 PM

Please note the "thanks to Penzoil for sponsoring this video" :wave:

They carefully leave out how long the "used" time was on the demonstration and what kind of abuse it saw. The major brands have been on a crusade to convince everyone of two things. The first is that the PAOIII oils they are producing are really "full synthetic" and will perform as well as a PAOIV or PAOV oil. The second is right in line with the PAO IV and V oils in claiming much longer engine life with very much longer oil change intervals, which is extraordinarily hard to actually prove one way or another.

I truly believe it is an "either/or" type decision. Sometimes you may get a bit of advantage with synthetic, sometimes not. Sometimes changing more often with conventional oil will be better than long intervals on synthetic, sometimes not.

What I also believe is that if you have a very high temp application, like turbos, the synthetic higher temp tolerance is a benefit, but go to a PAOIV to get max benefit. Air cooled engines which have a wide operating temperature range, can benefit from an oil with a high viscosity index and slower shear down, while water cooled engines in temperate climates would hardly know the difference.

I found it very interesting that some number of years ago, when all the "real" synthetics where trying to break into the market for high perf cars, that essentially all the roundy round racers were using Brad Penn non synthetic or blend racing oil, and as far as I know still are. The claim was that it is the additive package that makes the difference in high abuse situations, not the base stock, as it is always changed before the lower shear down rate would make any difference.

One thing I can absolutely assure everyone of is that this discussion will go on for eternity until the new "cosmic super special non oil engine lubricant" comes out and takes over the discussion.

ra2jim 09-05-2016 02:53 PM

Someday I want to find out if towing an ultra small car like a smartcar (1500#)is possible. I bet that will really shoot the mileage down. Of course it's counter to one of the reasons we got the smaller RT - small enough to drive anywhere w/out another vehicle.

mkguitar 09-05-2016 03:15 PM

what does your manual give for towing capacity?

the 2001 RT brochure shows 6100/1000 for your model with the optional hitch

RT has legacy model brochures available on their website

my PW is rated for 5000/500


mojoman 09-05-2016 04:56 PM

I had the opportunity to visit an large NASCAR RR facility a few years ago while I was helping a consultant friend of mine. I notice crates of 20-50 Mobile 1 motorcycle oil in their engine development/testing section. It was not the brand displayed on their cars.

booster 09-05-2016 05:31 PM


Originally Posted by mojoman (Post 47772)
I had the opportunity to visit an large NASCAR RR facility a few years ago while I was helping a consultant friend of mine. I notice crates of 20-50 Mobile 1 motorcycle oil in their engine development/testing section. It was not the brand displayed on their cars.

I can totally believe that. That is the basic "thumper" oil for the big Harley air cooled engines. It always had plenty of zinc and phosphorus, and was a PAOIV base. It may still be same or not, as apparently Mobil1 can be different based on what the application is. Getting information from them is near impossible, I have tried repeatedly. It has been rumored that the zinc is severely reduced in their water cooled motorcycle oils, and there are guesses on the thumper oil. Weather it is a group III or IV is up for grabs.

The old Mobil1 thumper oil was great stuff, I ran it in my turbo V8 hotrod for years without issue.

mojoman 09-05-2016 06:01 PM

You have to buy "racing oil" for off road use to get the higher levels of Zinc now days.

booster 09-05-2016 06:30 PM

somehow got two posts at once, :confused:

booster 09-05-2016 06:31 PM


Originally Posted by mojoman (Post 47775)
You have to buy "racing oil" for off road use to get the higher levels of Zinc now days.

It has also come back in some other products, too. Small engine oil, high mileage oil in some cases, "break in oil", some high performance labelled oils, classic car oil. You have to be careful with some of the racing oils, as they really are racing oils and very low in detergent and other street needed additives.

ra2jim 09-07-2016 02:53 PM

Mkguitar, brochure says Gcwr is 12500 and gvwr is 7700. But I understand I need to check my hitching setup and tires for their limitations too. With this much weight I might be tempted to try the synthetics. Curious to know what others get for mileage when towing.

ra2jim 09-17-2016 02:53 PM

Labor Day as I suspected was a traffic mess but thankfully no accidents. From home to campground was only 60 miles with a climb of 2000 ft. Rig was empty w 3 people...a disappointing 11 mpg...a whopping 27% less :(. This time I also had the fridge on dc while driving but never ran the onan the whole weekend. I was trying out a 400w solar generator which was charging on the cigarette lighter during the drive.

Nic7320 02-20-2018 03:43 AM

20 MPG is possible in a RT 170P
When I first bought my 1997 RoadTrek 170P, I headed off from California to Colorado and made my way back, and got 16.4 MPG averaged over the whole trip. I thought this was pretty good, considering the Colorado Rockies I had to traverse, but for most of this trip I also had to keep my speed down to 50-55 MPH due to a steering wobble problem (which was later fixed).

Later, I got a ScanGauge II and found the transmission was spitting out a PO740 code, indicating the transmission torque converter was not locking up as it should in fourth gear, and this reduces the gas mileage. I had the tranny serviced, on a trip to Arizona (RTR 2017), the ScanGauge-II indicated I was getting 20 MPG (long-term average), and even 21 MPG (long-term average) at times. I kept my speed about 55 MPH for most of the trip.

Unfortunately, the PO740 code has returned, and consequently my gas mileage has dropped, so the problem with the lock-up torque converter is not fixed.

P0740 means that the Powertrain Computer or PCM is seeing greater than a 200 RPM difference between the rotational speed of the Torque Converter and the Transmission Input Shaft.

The transmission problem might be something simple or something expensive, and cracking open the transmission is a messy job, so I'll have a shop do the work.

I'm looking forward to 20 MPG again! :flowers:

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