What the difference between Diesel engine oil....
Discussion
Pigeon said:
Oil for diesels has more detergents in it.
This is true in some cases, in others it is purly market research as most oils will do both petrol and diesel, in europe this is reperesented by the ACEA specs printed on the tin, A for petrol and B for diesel.
If the oil does not carry the B spec it cant be used in a diesel and so on.
Cheers
Guy.
Just found some more detail to help you. A bit technical but it was written by a chemist!
Traditional view was that diesel engine oils needed higher detergent level = TBN = alkaline reserve to cope with acidic combustion products derived from sulphur in the fuel.
The extra detergent also acted as a keep clean, diesel engines always produce more soot, inevitable because an over rich mixture is the only way to induce acceleration since there is no way of advancing the ignition.
Diesel engine oils also tended to be heavier, initially monogrades, later fairly heavy multigrades 15W/x or 20W/x to cope with higher bearing pressures resulting from high compressions.
Petrol engine oils traditionally needed improved anti wear not least because the engine turns faster, the valve springs have to be stronger to close the valve in time for the next cycle, so higher loading on the cam, followers and valve train generally.
These profiles are not necessarily mutually exclusive; technology has advanced, manufacturing tolerances are much tighter on all engines, diesels are more refined following development of the common rail engine, compression ratios and diesel sulphur levels have been reduced to address emission targets. Anti wear has recently been focused on the cam driven fuel pump which provides a very high pressure fuel supply to the injectors.
On the petrol engine side fuel injection has resulted in a smoother engine, more precise metering has reduced the likelihood of fuel dilution, valve train wear has been largely engineered out of the picture.
And of course the oils have been developed, it is now possible to attain high levels of overall protection and longer life from a low vis synthetic product.
So, diesel and petrol engine requirements have been getting closer, a properly selected low vis synthetic / part synthetic may be expected to be suitable for a range of modern diesel and petrol engines.
Hope this helps
Cheers
Guy
Traditional view was that diesel engine oils needed higher detergent level = TBN = alkaline reserve to cope with acidic combustion products derived from sulphur in the fuel.
The extra detergent also acted as a keep clean, diesel engines always produce more soot, inevitable because an over rich mixture is the only way to induce acceleration since there is no way of advancing the ignition.
Diesel engine oils also tended to be heavier, initially monogrades, later fairly heavy multigrades 15W/x or 20W/x to cope with higher bearing pressures resulting from high compressions.
Petrol engine oils traditionally needed improved anti wear not least because the engine turns faster, the valve springs have to be stronger to close the valve in time for the next cycle, so higher loading on the cam, followers and valve train generally.
These profiles are not necessarily mutually exclusive; technology has advanced, manufacturing tolerances are much tighter on all engines, diesels are more refined following development of the common rail engine, compression ratios and diesel sulphur levels have been reduced to address emission targets. Anti wear has recently been focused on the cam driven fuel pump which provides a very high pressure fuel supply to the injectors.
On the petrol engine side fuel injection has resulted in a smoother engine, more precise metering has reduced the likelihood of fuel dilution, valve train wear has been largely engineered out of the picture.
And of course the oils have been developed, it is now possible to attain high levels of overall protection and longer life from a low vis synthetic product.
So, diesel and petrol engine requirements have been getting closer, a properly selected low vis synthetic / part synthetic may be expected to be suitable for a range of modern diesel and petrol engines.
Hope this helps
Cheers
Guy
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