5W-30 vs 10W-30

[Slapshottr]

I am planning a trip to the Grand Canyon and Vegas and will be there the first two weeks of July. I would like to know if I would get any benefit from using 10W-30 vs 5W-30. My route has us traveling from San Antonio via Tucson on up to the Canyon. According to web resources avg temps in July for my route will be 82 to above 90. I currently live in the northeast and use Mobil One 5W-30 for the easier cold starting protection. My 2006 W24 owners' manual page 4-24 indicates both oils top out at the same temp.

[Slapshottr]

I am planning a trip to the Grand Canyon and Vegas and will be there the first two weeks of July. I would like to know if I would get any benefit from using 10W-30 vs 5W-30. My route has us traveling from San Antonio via Tucson on up to the Canyon. According to web resources avg temps in July for my route will be 82 to above 90. I currently live in the northeast and use Mobil One 5W-30 for the easier cold starting protection. My 2006 W24 owners' manual page 4-24 indicates both oils top out at the same temp.

[Joe Gilbert]

I'm sort of "old-school" but I feel that 5W is too thin for a hard working RV engine, especially in the heat of summer in the South West. I have always run 10W-30, Mobil 1.

[oemtech]

There was a thread a while back on this subject. It was the consensus that the close you get the numbers the better off you are. So, unless you are in a cold climate for any length of time go with 10w-30.

[rvten]

When we had our Winn. Adventurer on a W-20 chassis. I asked Workhorse about the 5w30 or 10w30 oil. They said for better gas milage stay with the 5w30. Engine was designed to run on 5w30. I used it all year long. Eveb Ford uses 5w20.

[DonavonP]

This write up is easy reading, humorous, and informative. The gentleman doesn't have a vested interest in skewing the information.

If you don't want to read the whole thing, scroll down to "Making Multi-Grade Oil". The quick summary is to make a 5/30 oil they start out with 5w oil. To make 10/30 oil they start out with 10w oil. From that base stock they add thickeners. The thickeners break down over time and extreme use. The guy is writing for the air cooled motor cycle engine which is almost as severe if not more severe than the 8.1 heavy truck engine.

[JC2]

When we had our 8.1 serviced just before winter at a WH service center, they put in 10W-30, which I also generally prefer. I could see using 5W-30 if you lived in where the winter temps were consistantly in the single digits or colder.

[kennersonf]

Slapshottr,

Add ten degrees to those average temperatures. I don't know where you got the information from, but those averages are a little low. I'm speaking from experience as I have live in Southern California and have experienced first hand how warm Vegas, Tucson and the Grand Canyon can be in July. I would even venture to say the average would be 95 to 105. The desert regions of Nevada, Arizona and California can be very harsh that time of the year. On our return trip from Texas last June, the temperature was 110 in Phoenix. Prepare for as high a temperature as 115 degrees. To make a long story short - go with 10/30. That's what I run.

[Full-Timers]

A while back Ford changed their requirement from 10W30 to 5W30. The reason, I am told, was something to do with meeting EPA requirements. Nothing to do with the engine or being a better oil.
Also I read where the "experts"� say you should run a single grade oil and if you must run a multi grade oil it should never have a spread of more than 20, ie: 10W30.
It says 5W30 on my oil cap but I run 10W30. I don't do freezing weather.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Full-Timers:
.... if you must run a multi grade oil it should never have a spread of more than 20, ie: 10W30.... </div></BLOCKQUOTE> The closer spread makes for a more stable oil formulation. Like you I don't see 0 degree weather.

[Slapshottr]

Sounds like 10W-30 is the oil of choice. Donavon P the link you provided was good reading. I'll change to 10W-30 for the warmer months. Thanks for the info.

[Steady Eddie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Joe Gilbert:
I'm sort of "old-school" but I feel that 5W is too thin for a hard working RV engine, especially in the heat of summer... </div></BLOCKQUOTE>
===============================
Joe--
x2..
The WCC has been around now, long enough, that there will be 2nd and 3rd Owners out there that
have no idea what type of care or oil changes
that their used rig had during its' life.
Under those conditions I'd like to offer up the
option of putting Mobil 1 15W-50 in there.
If you study DonavonPs link, you will see that,
the multi-grades lose the upper viscosity number
over time. 10W-30 becomes like 10W-25..the 15W-50 also becomes more like fresh 10W-30, but in a
used engine, it still has some body to it and some cushioning properties. Going back to the DonavonP link, it defines what the "C" means as printed on the bottle of M1 15W-50: Commercial.
A Diesel Additive Package, which is a very good thing and something the other M1 Grades do not have. It is like a Delvac 1 Additive Package.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Steady Eddie:
Under those conditions I'd like to offer up the
option of putting Mobil 1 15W-50 in there.
</div></BLOCKQUOTE>Use of viscosity greater than 30W on the 8.1L engine is not supported by General Motors or Workhorse. 10W-40 is also another viscosity that is not supported as well.

I would suggest that an owner stay the course with 5W-30 or 10W-30 as specified in the owners manual.

I am assured that the viscosity rating on my synthetic oil remains stable throughout it's interval service life which for me is is not greater than 6000 miles or 6 months. I feel confident that my oil's upper viscosity number will not change during this time.

The recommended oil change interval and service life on a new Workhorse 8.1L engine is 3 months and or 3,000 miles WCF using dino oil. Throughout this period of time the viscosity of the oil should remain stable.

[Tom N]

Oil heavier than 30W in the 8.1 may cause piston ring sticking per Workhorse and GM.

-Tom