Any harm to an old gas engine using diesel oil?

[Rebel Rouser]

I know this subject has been brought up before, but I need my own advice.

Specifically, I was told by a mechanic, that a 1974 Ford 391HD V-8 gas truck engine cannot use a CI-4/SL rated 15W40 motor oil, because it contains too much detergent.

This particular vehicle is a firetruck pumper, and has only 9,300 miles on the odometer(I don't recall the exact engine hours)and is the only gas powered one in the fleet. The rest are diesels, and the FD has a 55 gallon drum of the 15W40, so rather than buying different oil for the gasser, I suggested using this, as it has the SL rating.

Cold cranking is not an issue, as the fire station is heated. I think the higher detergency would actually be beneficial.

Thanks!

 

[Shannow]

With so few miles on it I'd say no harm.

I've seen a few very old oil burning (heavy consumption) that will foul plugs when run on fleet oils.

 

[Bogatyr]

Rebel Rouser,
I've got a 1970 Land Rover with 41k on the clock that I'm running Rotella 15w40 in it specifically because of the extra detergent. I have no idea how long the engine sat before I finally got the truck on the road again. So, I did the first oil change after a few hours of running, the next after 100 miles, then 300, now I'm coming up on 500 miles on this oil and I'll change it soon. I think I'll do a UOA on the next batch of oil that comes out just because even after 500 miles, it's still pretty black. I'm thinking I'm still in the cleanout phase now.

Bogatyr

 

[jthorner]

Mechanics who really understand oils are few and far between in my experience. Mechanics and parts counter guys often seem to be full of "knowing" advice which has little or no basis in reality.

I cannot see anything wrong with running an HDEO in your application.

John

 

[TC]

RebelRouser: This quote merely confirms what you evidently already know, just to put your mind at ease. "SL" supersedes the "SE" gasoline oil specs of 1974.

"A design criterion for new categories is that the performance requirements of later categories exceed the performance requirements of all previous categories. Therefore, APH SL oils will be superior in performance to SJ, SH, SG, etc."
http://www.citgo.com/Products/LubesOils/EngineOilClassification.jsp

As long as you have the SL rating, it meets current spec's for gasoline engines, including the latest 2004 engines which may be most vulnerable to ash deposits by cal and mag detergents, and cat converter contamination by anti-wear agents zinc, phosphorus, etc. If it won't harm a 2004 Ford Pickup engine and smog system, it certainly won't phase your '74 Ford gasser truck (although the comment by Shannow was enlightening). Some diesel engines specifically call for a "low ash" oil, but this shouldn't apply to your ride.

Two typical oil spec sheet quotes to add to your "warm & fuzzy" factor:
"Shell Rotella T Multigrade exceeds requirements of today's high-performance, fuel efficient, low-emission diesel and gasoline engines..."
"Chevron Delo 400 oils are mixed-fleet motor oils recommended for all four-stroke gasoline and diesel engines operating under severe service and subjected to wide variations in climatic conditions."

[ March 02, 2004, 07:17 PM: Message edited by: TC ]