I have a 328i, 1995 model with Nikasil block. According to BMW South Africa
it is fitted with a different thermostat which causes higher combustion
temerature and therefore eliminated the need to worry about sulphuric acid
forming and eating away the Nikasil coating.
If I'm not mistaken, this means that the engine runs hotter than other
engines. How much hotter? Does any old 20W50 oil do the trick, or should I
look for an oil that is specifically formulated for these extreme
temperatures. Or is my concern unfounded?
The car has used a bit of oil since its last service which was about 7,000km
ago and I want to top it up. I think the workshop used Castrol oil with an
SGCF rating if that means anything to anyone. I can't find an oil like this
on the shelves in my local spares shop.
You should find plenty of oil rated to API SG or SL combined with CF4 or CI4
which are superior and newer ratings. These will usually have an SAE
viscosity of 15w/40 for heavy duty use even in very hot climates.
The CF, CG4 CH4 and all C ratings are heavy duty, high detergent diesel
ratings but can be combined with petrol ratings to produce what are called
'multifleet' oils suitable for both petrol and diesel engines. These are
superior oils to petrol only type as long as the viscosity is suitable for
The Thermostat and ECU reprogramming were both part of a service
campaign (12 09 94 - 4132) as an early attempt to head off the sulfur
corrosion of the nikasil liners. I do not believe that either of these
modifications were successful if the car was run with high sulpher fuel
it still wore the linings. In that campaign the 85 degree thermostat
was replaced with a 95 degree one.
I have a 94 540i which originally had the nikasil block. It was
subsequently changed to an alusil one by BMWNA. Interestingly, the
thermostat in mine was still the higher temp one and the ECU was not
reprogrammed back to original after the block swap.
As a part of a recent major service inspection (which I performed) I
replaced the higher temp thermostat with a Wahler 85 degree one,a s well
as replacing the original hard plastic thermostat housing with an
aluminum aftermarket one.
BMW South Africa confirmed that my car has an Aluminium/Nikasil block. BMW
donated a number of these vehicles to the South African Police way back in
1995/1996 and ran them each with a 200,000 km service plan. Even though the
Police destroyed most of them in accidents, a few survived that and made
200,000km without any problems (according to BMW).
In my view 2.8 is hardly a small six, but you are right, the smaller 2.5 and
2.0 sixes were not brought to SA with Nikasil. Only the 2.8 was sold here
and only for six months or so after which cast iron blocks were
I am not familiar with what BMW SA did regarding the Nikasil V8s.
Getting back to the oil issue. Should I just top-up with an oil recommended
for diesel engines?
MW de Jager
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