Diesel oil in a petrol engine

[BZ Touring]

Lads. The wagon's in for a service (96 BZ Touring), and I have been advised to use Castrol RX Super Diesel to give the engine and seals a bit of a recondition in an attempt to reduce oil consumption. This will be just a one off, next service normal oil (15W40) will go back in. Any thoughts (constructive ones based on experience, not obvious ones based around "diesel oil probably shouldn't go in a petrol engine"). Cheers.

[Chickenman]

Pretty much all oil has seal recondiitioning additives etc, I can't see why diesel oil would have too much more.

Can't recommend any specific oil but if it's going through a bit of oil (which is normal for a blacktop.. especially if you drive it cold) and there is none on the ground it's obviously not your seals.

Use the best oil you can afford and be prepared to top it up every so often it's just the way it is for blacktops (they're getting up over 100 000 km's now).

I'm not entirely sure the problem would disappear after a complete rebuild anyway.

[BZ Touring]

Yeah, to be fair it's not using a hell of a lot of oil (at least no more than would be expected based on feedback from this forum).

Apparently the diesel oil is better at cleaning engine deposits. So as long as there are no negatives, I can't see why not. It might turn out to be the magic atedote to all the interesting issues that crop up with 20 valves

[evil_si]

i run my cars on a diesel oil, mobil delvac 15w40 permanently,

surprisingly considering the detergent and carbon retaining properties diesel oil has, i find it stays clean for longer periods,
ie still goldy after 5000km, and the car has done 260000k

[Jebus]

Diesels oils do have detergents in them to clean up the by-products of diesel combustion, by-products that petrol engine dont make and the detergents can be harmful to a petrol engine, even losing compression.

Diesels run much higher compression therefore much more heat and the oil is made to suit this.

You can run it for a couple of hundred kays to flush the engine (not something I would do on a blacktop), but running it for long periods of time will do no good, most probaly bad. Id just give it a 15 minute flush with kerosene then carry on running good oils. "High mileage Oils" have seal protectant additives so give them a whirl if youre really concerned.

[BZ Touring]

Interesting. Why would you not do an engine flush with a black top?

[BZ Touring]

Also, what compression do diesel engines typically operate at? The reason I ask is that I understood that 20 valves also run at quite a high compression (relative to other petrol engines that is).

[Jebus]

Its still a relatively new motor, as you said before yours doesnt have a problem, its fine. Wether or not you flush it isnt going to make a difference, you arent going to goin horsepower, you wont notice a thing.

Only possibility is that you might damage your motor, better of leaving it how it is and running nice oil.

[Jebus]

Also, what compression do diesel engines typically operate at? The reason I ask is that I understood that 20 valves also run at quite a high compression (relative to other petrol engines that is).

Between 15 to 20:1 typically at the higher end of the scale, against a blacktops 11:1. Diesel engine takes in air, compresses it massively and the fuel combusts from the heat of the compressed air, no spark like on a petrol engine.

[BZ Touring]

Yeah, nah, yeah. Increasing horsepower isn't my motivation. Just trying to keep the engine in good nick.

[Jebus]

Yeah, nah, yeah.

Yeah or Nah??

Increasing horsepower isn't my motivation. Just trying to keep the engine in good nick.

Just look after it run good oil and a good filter.

[strx7]

i have personally seen 2 engines come into work which accidently got deisel oil in them. both siezed big ends and or mains as a result, but man they were clean inside......

[sergei]

I don't see diesel oil siezing bearings. In fact diesel oil theoretically should be better for bearings aswell, because of stress involved on the bearings is much higher than on petrol, due to compression and near detonation self ignition. Also diesel pistons are very heavy. Have you noticed how diesel engine clanks on idle?

Diesel oil has got lots of detergent additives, because of that it could be bad for seals. Anyway for some reason diesel use different compound for seals.

[Mr Revhead]

i wouldnt run an engine for 15mins on kerosine

[evil_si]

i wouldnt run an engine for 15mins on kerosine

i would if i wanted to do a destruction test

[sergei]

on idle nothing will happen - for really long a while (untill kerosene reaches flash poin that is) probably would be spectacular at the end...

[Jebus]

Heh, yes only on idle, and with the old oil in it still.

Works a treat, fixed all the blackening of oil problems in the smallport.

[Mr Revhead]

hehe thats a better option

i have previosuly used ATF for that.
in a townace where i too out the bung and nothing came out.....

[Ae92typeX]

Ive run diesel oil in some cars for big k's without issue. Both compression and spark based oils have their rating on every oil pack. Some new diesel oils are at an 's' rating which is equal to what most cars here require.
If it was damaging to a spark engine, why would it have a rating?
anyway, from experience, Ive had no issues at all, but everyone is entitled to their opinion

[Mr Revhead]

interesting tren iv noticed is ppl buying magnatec for thier surfs