Using Diesel rated Oil in Gas Engines

[enjr44]

I started the thread on the use of zinc (ZDDP) in flat-tappet gasoline engines. The consensus was that ZDDP was needed, or at least good for them and prevented cam and lifter scuffing. I started the same thread on the Mazda Trucking Forum. I hang around there because I rebuilt this (http://s1087.photobucket.com/user/enjr4/library/Mazda B2200) from an abandoned B2200 I found in a neighbor’s back yard. Between me and the JYs I think it came out pretty good. Anyway . . . . . .

That thread turned into a discussion (argument) on using diesel rated oils in gasoline engines. One of the arguments against was that because combustion temperatures were higher in gas engines the type of detergents used in diesel oils would break down and build up sludge in the heads; blocking the oil passages. Others said that was BS and it would do no such thing.

I am considering using Rotella T (a diesel oil with ZDDP) in my flat-tappet 4L Ranger. It has 155K miles on it and I am a little worried that if the diesel detergents are that good it will wash any crud out of the engine and screw things up (like the oil pump).

I would like to know what you all think??

Ed

 

[wildbill23c]

I'm not too sure on engine oils, but I would think that putting that oil in your engine and having it clean the internal parts of the engine would be a good thing. What I would do is do the oil/filter change, then drive the truck for about 100 miles in a continuous drive that would get it heated up enough I would think to break everything up. Bring it back home, change the oil and filter again, possibly drop the oil pan and clean everything out at that time, that will also give you a better idea of if your engine is really dirty inside as well.

 

[Schnot]

I think it would be fine. I've got several diesels and run a small trucking business so usually have rotella in a drum. I've run it in my ranger and dirt bikes before and had no ill effects. It gets really thick when it's cold though so it might make winter time starting issues if you in a cold region.


Sent from my iPhone.

 

[adsm08]

The worst thing you might have is a lot of new leaks.

Gas doesn't really burn that much hotter than diesel. If you are changing the oil regularly it won't break down. Also, most of the sludging from running diesel oil is actually caused by sludge that already exists in the engine being cleaned out and washed back to the bottom.

 

[exbass94]

Diesel oil will not sludge up just because it's used in a gas engine. Period.

4.0s have flat tappets? I thought they had roller cams. I use regular 5w30 in my 4.0, same as 99% of people who also have 4.0s. You don't hear of massive cam failures. Flat tappet cams don't NECESSARILY need a lot of ZDDP. A regular stock engine with low valve spring pressures does NOT need a lot of ZDDP, even if it's flat tappet. A high performance racing engine with high spring pressures, yes.
And ZDDP is not the end-all be-all of anti-wear additives. API SN oils don't have as much ZDDP, yes, but they have OTHER anti-wear additives that work just as well as ZDDP.

 

[85_Ranger4x4]

As long as you keep it in the correct grade. It is kinda hard to find diesel oil in anything other than 15w-40. Sometimes you can find it in 10W-30 but it isn't common at all.

 

[cammeddrz]

here comes a small thread-jack

I have rotella in a drum. I've run it in my dirt bikes before and had no ill effects.

^^ my favorite internet forum myth

motorcycle forums would have you believe rotella T will give you "no ill effects"

but it still has Moly in it, and enough to shorten the lifespan of wet-clutch discs by at least 25%. Moly plugs up the fiber discs, and shortens the life of the clutch, of the thousands of motorcycle brought to me while working at dealership. every time a person brought me a bike on which the clutch failed waaaaaaay too soon. the answer was always "yes" to "were you running auto/diesel grade oil like Rotella T?..."

and the answer was always "no" to the follow-up question of "did it really end up saving you any money now that you need to buy a new clutch?..."

but most guys don't see the failure soon enough to for them to make the connection and attribute it to the oil. so when their clutch only lasts 150 hours, instead of 250 they don't realize it was because of them being cheap-skates on their oil, they always say "I've been running it for 75hrs, with no ill effects"

on a wet-clutch system run "JASO", or "MA" grade oil

 

[Schnot]

Makes sense about the clutch. I just figured my clutches failed because I beat the hell out if them. They're fairly cheap and easy to replace so I always use them hard like they're supposed to be used.


Sent from my iPhone.

 

[fastpakr]

Makes sense about the clutch. I just figured my clutches failed because I beat the hell out if them. They're fairly cheap and easy to replace so I always use them hard like they're supposed to be used.


Sent from my iPhone.

Is Rotella T not JASO MA rated? The T6 I've run in the past was.

 

[pjtoledo]

I ran 15-40 diesel oil in my Taurus SHO for several years. Thats the Taurus with a 3.0L V6 with mechanical flat tappets that makes regular trips to 7000 RPMs. Started putting it in somewhere around 125,000 miles until it retired at 175,000.
Compared to the 10-30 synthetic stuff it sounded quieter and seemed to run smoother. No problems with excessive use, leaks, or sludge.
(never got around to trying it in the clutch, couldn't find the fill plug)

Perry