A while back, I thought I saw some threads on the topic of using 15W40 engine oil in our vintage engines. I was wondering if you guys could refresh my memory on whether it is a good or bad thing, as I'm about to change my oil and I can get all the 15W40 I want for free, as opposed to buying Mobil 1 synthetic like I did last oil change. My shop manual says to use 20W40, my owners manual says 10W30....and I don't know enough about oil viscosities & the like to make an educated decision on my own. Once again, thanks in advance!!
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Re: Using 15W40 Diesel engine oil-'70 LT-1
i've used dexon engine oil for years--its formulated for diesel engines. my john deeres and vettes love it. buy it in bulk from Exon distributor--comes in 1 gal or 5 gal or 55 gal drums. way less expensive than Mobile.mike -
Re: Using 15W40 Diesel v Mobile 1
Have been reading a lot on oil to use on older auto's. It appears that the newer oils rated SL lack an EP, extreme pressure, additive (zinc or phosphorous based). I found that my new bottles of Mobile 1 ar now also rated SL. A friend called Mobile 1 (had some older rated oil with EP still in it) to ask their advice -- was told not to use in pre 1980 vehicles since the seals are not compatible and will leak. Looked under by 64 and rear main had drips, but never did before last year when I changed to Mobile 1. Engine rebuilt in 70's with only 5K miles on it now. If your motor was rebuilt after 1980 you may be alright, but ask somebody with better knowledge.
Now back to the EP question. GM sells an additive of EP called EOS (Engine Oil Suppement that articles have been recommending, so check your diesel oil for rating also. Please note I'm not an expert on this subject, but wanted to get the information out to you. PS, now using ValvolineRace Oil "Not Street Legal" part number VV850. It does not last long, but I don't drive much so a yearly change my requirement.Comment
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Re: Using 15W40 Diesel engine oil-'70 LT-1
The IMPORTANT issue is to make sure the oil meets the API CI-4 service specification. Read the label. This is the currect spec for HD diesel engine oil, and any oil so labeled has a better detergent, dispersant, anti-wear, and anti-corrosion additive package than API SL oils for spark ignition engines. This holds regardless of the base stock oil - mineral or synthetic.
The proper viscosity is a function of the ambient temperature range that is expected for cold starts over the time the oil will be in the engine.There is some variance among manufacturers, but as a rule, most say a 15W is okay down to about 10 degrees F and a 40 is okay for the highest expected including desert summers.
GM manuals of your car's era say that SAE 30 is suitable if cold start temperature are not expected to drop below 40F.
Suggest you visit:
www.api.org
To learn more about motor and gear oils.
DukeComment
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Re: Using 15W40 Diesel engine oil-'70 LT-1
Jeremy-----
The 2 most prominent engine oils used for HD diesel truck engines (at least, here on the west coast) are Shell Rotella and Chevron Delo. Both of these oils carry the diesel spec "CI-4" that Duke mentioned. However, these oils ALSO carry the gasoline engine API rating of "SL". So, if it's a concern, they are fully approved for use in gasoline engines as well. In fact, if they made these oils in a viscosity that met current passeneger car requirements (which they don't), you could use these oils in brand new cars as well as old ones.
GM has rather recently issued a new standard for oils for use in gasoline engines. This standard is GM 6094M. This standard applies to most current GM gasoline engines except those that require oil meeting standard GM 4718M. The latter standard applies to 92+ Corvettes and certain other cars using "Corvette-like engines". Essentially, the 4718M standard means that you have to use synthetic oil; I don't think that there is any conventional or "blended" oil which does meet it.
The 6094M standard is not necessarily "synonomous" with API "SL", the current "highest" API rating. There may be oils which meet the "SL" standard which don't meet the GM 6094M. Unfortunately, you will not find a statement to the effect that the oil meets standard GM 6094M either on the containers nor the web-sites of most of the popular motor oils. After researching it a bit, though, I can tell you that oils of 5W-30 and 10W-30 of the following meet the GM 6094M standard:
Mobil 1 Synthetic (also meets GM 4718M)
Shell Formula
Shell Synthetic (also meets GM 4718M)
Castrol
Pennsoil
Pennsoil Synthetic (also meets GM 4718M)
I expect that other oils meet the GM 6094M standard, also, but these are the ones that I KNOW do.In Appreciation of John HinckleyComment
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Re: Using 15W40 Diesel engine oil-'70 LT-1
I have used "diesel" oils for over 40 years now in everything that I have owned. Texaco URSA, Shell Rotella. Always found engines to be very clean on the inside when replacing valve cover gaskets. Have had some very high mileage passenger car engines (250,000+) with NO bearing, piston or ring failures. Just sold Chev pu with 175,000+ miles, less that a quart of oil comsuption in 4,000 miles.Dick WhittingtonComment
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Re: Using 15W40 Diesel engine oil-'70 LT-1
I think Ol' Blue is gonna get the Rotella diesel oil this year. If it's good enough for a Link Belt 278, then it'll probably be fine in my LT-1. I will, however, be more aware of the ratings and standards. I guess I assumed that all of today's formulations meet current standards.....I also appreciated all the info on the PF454 oil filter in the threads above, as I too was a bit confused when I went to Autozone. I'm trying to get the corresponding number for Baldwin filters...we use them on our cranes, and all of our mechanics say that they are the best, at least for diesel applications.Comment
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