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Is Engine Oil the same for Petrol & Diesel engines ?

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1st Gear

 

Just curious, if there are some engine oil left-over from a car's servicing, can it be used

to top-up a diesel engine ? (e.g. Shell Helix Ultra 5w-40)

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Neutral Newbie

Yes you can. Diesel and car engine oil is pretty much the same. Some specialised diesel oils may contain slightly more detergents since diesel engines tend to be "dirty"

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Neutral Newbie

diesel oil in petrol engine yes.

 

petrol oil in diesel engine, no.

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Neutral Newbie (edited)

diesel oil in petrol engine yes.

 

petrol oil in diesel engine, no.

 

But I thought they are the same thing? Cause eg for BMW LL04 specs, Its specified for both petrol and diesel engines and any LL04 specified oil will run fine on both petrol and diesel engine.

 

There is also the Amsoil Premum protection 20W50 (which I am using it now). Its specified for both petrol and diesel engines.

Edited by Mini-itx2010

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Neutral Newbie

Diesels tend to use thicker oils..

 

It's true diesel engines are dirtier and I believe diesel specified engine oils contain more detergents to clean up the engine..

 

 

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Neutral Newbie

For TS case, top up should be fine in small amounts.. the engine oil would be much thinner if you top up a lot with the 5w40 oil..

 

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5th Gear

Correct me if I'm wrong, but I believe engine oils have ratings listed on the label if they can be used for petrol, diesel or both. The petrol code usually starts with "S" (latest one should be SJ or SM) while diesel starts with "C" (for instance CF, CI-4 or CJ-4). Check your engine oil for this rating (If you're talking about Shell Helix Ultra I believe it has both S and C ratings) and should be OK to use in diesel engines. However, I kind of remember that Shell Helix Ultra 5W-40 has only a CF rating for diesel, so your vehicle is one of the newer turbocharged diesels, it might require oil with a minimum rating of the newer CI-4 or CJ-4 standards, so better to check with your vehicle manual.

 

If the oil label has only an S rating, it probably isn't suitable for diesel engine and better not try.

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5th Gear

as long as the required API ACEA..etc specs are met

petrol and diesel oil can be used in each other

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1st Gear (edited)

Agreed. As long as it meets the specified specs, you can use on either.

 

"Specialized petrol oil" usually have more additives to deal with sulphur, which is bad for petrol engines, but actually no big deal for diesel engines. So there is some conflict leading some to differentiate "petrol oil" and "diesel oil".

 

Usually only very expensive "petrol oil" also meets the specs for "diesel" oil.

Oils made specially made for diesel engines tend to have much more detergents to deal with soot, carbon etc.

 

Because of the high cost of "petrol oil" that meets both specs, most people would rather go for the "specialized diesel oil" if they are running diesel engines as it is probably only 1/2 the price since they dont have to meet "petrol engine specs".

Edited by Asure7

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1st Gear

BMW has actually published a technical bulletin that LL-04 must not be used outside Europe due to fuel quality issues.

 

Typically, the low-SAPS formula is very good for euro-IV and euro-V diesel engines. But because of this new formulation, there is less additives which are previously good for petrol engines which make them more resistant to acid corrosion. Think this way: The previous additive package is what causes more ash, to reduce the amount of ash, they have to use less additives if they intend to use the same type. Well, of course, unless they have introduced alternative additives that can deal with that. But the general consensus is unless we know for sure, and bmw approve LL-04 is ok to be used outside Europe, LL-01 is still better for petrol engines.

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Supersonic

Diesel engine oil are heavily additized to deal with soot, while petrol engine oil doesn't need to.

 

If the oil has dual ratings for API S and C, then it should not be a problem, especially if using only a small amount for top-up.

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1st Gear

Just curious, if there are some engine oil left-over from a car's servicing, can it be used

to top-up a diesel engine ? (e.g. Shell Helix Ultra 5w-40)

At least better than lack of engine oil

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2nd Gear

Still so much mystery in engine oil till this day.

 

If use wrong oil for diesel engine.....how bad can it in real life? Lifespan of diesel engine and the exhaust valves premature damaged within ten years lifetime?

 

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Clutched

Still so much mystery in engine oil till this day.

 

If use wrong oil for diesel engine.....how bad can it in real life? Lifespan of diesel engine and the exhaust valves premature damaged within ten years lifetime?

Depends....

If euro4 engine....dun use 'chlin chai' oil.....need 5-40w grade lub oil of course minimum CF ratings....else the 'small' turbo engine will be short lived :D

 

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1st Gear

Euro-IV engine will seize and cannot be restarted if wrong oil is used.

Must send back to agent to reset.

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1st Gear

Correct me if I'm wrong, but I believe engine oils have ratings listed on the label if they can be used for petrol, diesel or both. The petrol code usually starts with "S" (latest one should be SJ or SM) while diesel starts with "C" (for instance CF, CI-4 or CJ-4). Check your engine oil for this rating (If you're talking about Shell Helix Ultra I believe it has both S and C ratings) and should be OK to use in diesel engines. However, I kind of remember that Shell Helix Ultra 5W-40 has only a CF rating for diesel, so your vehicle is one of the newer turbocharged diesels, it might require oil with a minimum rating of the newer CI-4 or CJ-4 standards, so better to check with your vehicle manual.

 

If the oil label has only an S rating, it probably isn't suitable for diesel engine and better not try.

 

oic ... Guess it is better to buy separate oils for the engines in order not to damage them.

 

Thanks for the advice, never thought there are so much knowledge into engine oils.

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Supersonic

Not all Euro 4 engine needs 40 grade oil. My caddy using 5W-30, which meets the VW requirement.

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