Oil for 8.1 Vortec in 12 ton Motorhome

[vettenuts]

OK, just found this in my Workhorse manual (Workhorse is the chassis manufacturer, GM was the engine builder). Not sure Rotella is a good option now.

On page 18 of the Chassis Guide published there is a chart showing the recommended oil viscosity for their gasoline engines. In the bottom right corner of this chart it clearly states "DO NOT USE SAE 10W-40, 20W-50, or any other grade oil not recommended."

In addition, outside and just below the chart, there is a more definitive explanation paragraph that says "NOTE: 10W-40 has been removed from all Workhorse recommendations..........Testing showed 10W-40 oils tended to be more prone to ring sticking......Workhorse also does not recommend 20W-50 motor oils."

With the note on ring sticking, now am wondering if Penzoil Ultra Platinum or Penzoil Platinum might be a better choice even though the viscosity is near the bottom of the 30W range at 100 degrees.

 

[Kuato]

Agree with Rotella T6 5w40.

 

[kschachn]

All that has nothing to do with T6 5W-40. It is an ancient warning from back in the day when wide viscosity spread oils were inferior. A lot of owner's manuals from many years ago had such statements. It does not apply today.

Originally Posted By: vettenuts
OK, just found this in my Workhorse manual (Workhorse is the chassis manufacturer, GM was the engine builder). Not sure Rotella is a good option now.

On page 18 of the Chassis Guide published there is a chart showing the recommended oil viscosity for their gasoline engines. In the bottom right corner of this chart it clearly states "DO NOT USE SAE 10W-40, 20W-50, or any other grade oil not recommended."

In addition, outside and just below the chart, there is a more definitive explanation paragraph that says "NOTE: 10W-40 has been removed from all Workhorse recommendations..........Testing showed 10W-40 oils tended to be more prone to ring sticking......Workhorse also does not recommend 20W-50 motor oils."

With the note on ring sticking, now am wondering if Penzoil Ultra Platinum or Penzoil Platinum might be a better choice even though the viscosity is near the bottom of the 30W range at 100 degrees.

 

[Garak]

Originally Posted By: vettenuts
Can Rotella be used in a gasoline motor? Seems that some of what I have read here indicates that is a no-no. I will look into the T6 and the Castrol 0W-40. Mobil-1 0W-40 might also be an other option.

Yes, it can. Delvac 1 is also another good option, in either 5w-30 or 5w-40, along with the other options you and others have listed. There's nothing wrong with using Pennzoil Euro A3/B4 grades, either, though availability might be a bit of a problem.

I would gather that Rotella would be likely the easiest to find anywhere on the road and at a sensible price.

 

[c502cid]

8.1 is not picky on oil nor have any of the past 2 and current 8.1 I've had used oil. I've run mostly 15w-40 in summer, and 5w-40 in winter, although I've run 5w-30, 10w-30, conventional and synthetic and different brands.. It really hasn't mattered. I pull about 12k lbs with it, not as heavy as you but just my experience.

 

[DoubleWasp]

Big blocks love T6. And yes, perfectly fine to use in a gas engine.

 

[TiredTrucker]

Unless the engine is pretty worn, I am not sure why a 10w30 wouldn't do just fine. My factory remanned 12.7L Detroit (currently with 601,000 miles on the reman) does just fine on a HDEO 10w30 syn blend and it was built around the same time the 8.1 hit the market. So, no earthshaking technology in the engine. Using a HDEO 10w30 would be a reasonable choice.

 

[ChrisGuerrero]

Hi @vettenuts - Rotella T4 15W-40 (replacing the Rotella T 15W-40), or the synthetic Rotella T6 5W-40 will do an excellent job of protecting your engine. If you expect to start up in freezing weather you will appreciate the low temperature flow properties of the synthetic T6. Rotella is readily available from parts stores and big box stores as it is possibly the most popular diesel engine oil available. Let us know if you have any additional questions! You can give us a call at (800)237-8645. - The Shell Rotella Team

 

[DoubleWasp]

Originally Posted By: TiredTrucker
Unless the engine is pretty worn, I am not sure why a 10w30 wouldn't do just fine. My factory remanned 12.7L Detroit (currently with 601,000 miles on the reman) does just fine on a HDEO 10w30 syn blend and it was built around the same time the 8.1 hit the market. So, no earthshaking technology in the engine. Using a HDEO 10w30 would be a reasonable choice.


I can only tell you from having seen plenty of these torn down; but big block engines do not appreciate being spun long and hard on 30.

 

[TiredTrucker]

I suppose. The several 454's I had didn't seem to mind.

 

[Stewart Fan]

I had an '01 2500HD with the 8.1

Towed a travel trailer and a boat and put about 75k on the truck. I did multiple UOAs with 10w-30.

I never had a bad analysis running 10w-30

 

[Ryan02SS]

My 06 boat Mercruiser 496HO 8.1 specs 20w40. Base engine is a stock GM 8.1 longblock. Using mobil delvac 1300s 15w40 at 25-30hr oil change intervals. Spends a lot of time at 4000-5000rpm. No oil usage at these intervals. Earlier 01-04 8.1's were prone to oil usage with light weight oils due to faulty intake manifold gaskets. Later models this was corrected.

https://youtu.be/-wBZgVsyNlI

 

[CONMCK]

Before deciding on whether a -30 or a -40 is better your owners manual is a good place to start, and I'm assuming your workhorse has an engine oil cooler. So the question is what would the viscosity of the oil be at running temperature? I'm thinking good quality 5w-30 would be fine.

 

[vettenuts]

Originally Posted By: CONMCK
Before deciding on whether a -30 or a -40 is better your owners manual is a good place to start, and I'm assuming your workhorse has an engine oil cooler. So the question is what would the viscosity of the oil be at running temperature? I'm thinking good quality 5w-30 would be fine.


Owner's manual specifically states not to use a -40 oil.

 

[rrounds]

Originally Posted By: vettenuts
Originally Posted By: CONMCK
Before deciding on whether a -30 or a -40 is better your owners manual is a good place to start, and I'm assuming your workhorse has an engine oil cooler. So the question is what would the viscosity of the oil be at running temperature? I'm thinking good quality 5w-30 would be fine.


Owner's manual specifically states not to use a -40 oil.

But if you read Ryan02SS post, he has the same block(more HP) as you and his engine takes 20/40. A boat never goes down hill, its on the gas all the time. You have a motorhome that is 12 tons and even going on a straight road the engine is working hard, my class A is 11 1/2 tons loaded and I run Rotella 5/40 with 42k miles on my '08.

ROD

 

[FlyNavyP3]

I would argue that although the boat has a higher specific output the operating environment is very different for the boat. The boat has a nearly unlimited heat sink available to it and likely operates with a lower coolant and oil temperature than the engine in the motor home. I can't see any reason to stray away from the manufacturer recommended oil weights in the manual. Find an oil that meets those specs that also meets the owners requirements to source while on the road. I'd say Rotella T5 10w30 fits that bill as I've never seen a Walmart that didn't have plenty on the shelf.

 

[kschachn]

Originally Posted By: vettenuts
Owner's manual specifically states not to use a -40 oil.


As was explained, the prohibition has nothing to do with the grade but with the poor quality of wide-viscosity spread oils from days past. A XW-40 oil of today will not harm your engine.

 

[FlyNavyP3]

Originally Posted By: kschachn
Originally Posted By: vettenuts
Owner's manual specifically states not to use a -40 oil.


As was explained, the prohibition has nothing to do with the grade but with the poor quality of wide-viscosity spread oils from days past. A XW-40 oil of today will not harm your engine.


The GM 8.1 is hardly an engine from days past. It was first used in the GMT800 in 2001 and ran to the end of production in 2007. To the best of my knowledge it is still offered in the workhorse chassis produced by Navistar. I would not be so quick to disregard the recommendation of the manufacturer to not use a 40 weight oil. It is not like we are referencing the owners manual of a mid-1970s vehicle used for towing or any other severe service. It could be argued that a quality 40 weight oil might work well in service however the manufacturer has to assume that there is a wide variety of 40 weight oil's of which several may not be sufficient to accomplish the goals established in the design of the engine or from issues that have been revealed by in-service use. Therefore considering the recency of the engines design and the recommendation of the manufacturer why risk it? Why subject yourself to disproving the manufacturers claim that damage may result, why speculate? Why not just pick a suitable 30wt that meets both the OP request as well as fits within the specifications of the manufacturer?

 

[Shannow]

Bear in mind that the J300 Standards still only required 0W, 5W, and 10W40 to have the same 2.9HTHS as a 30 grade, reflecting the way that 10W40s were built in the early days.

Only in 2013 revision was the 0W, 5W, and 10W grade required to man up to a 3.5HTHS reflective of what a 40 should have been.

kschachn's assessment is on the money IMO.

 

[FlyNavyP3]

Originally Posted By: Shannow
Bear in mind that the J300 Standards still only required 0W, 5W, and 10W40 to have the same 2.9HTHS as a 30 grade, reflecting the way that 10W40s were built in the early days.

Only in 2013 revision was the 0W, 5W, and 10W grade required to man up to a 3.5HTHS reflective of what a 40 should have been.

kschachn's assessment is on the money IMO.


Shannow I usually agree with you, however the HTHS likely isn't the reason GM recommended against 10w40, also I worry when absolutes are used as I don't agree that ANY 10w40 is suitable. I would concede that a SM/SN rated 10w40 from XOM/SOPUS/ASHLAND would likely work well and present without issue in the application. However my question is still why? How many trouble free miles does this engine already have that have been on likely passenger car spec 5/10w30? What is to be gained from the 10w40? With a roller cam, ample main and rod bearing sizes, a taller deck and longer rod compared to a traditional BBC that reduce skirt loads does this engine need a 40wt? I say no, it doesn't and will likely be taken out of service due to another issue before the engine requires an overhaul. OP is free to draw their own conclusions.