Changing oil grade/oil cooler question

[tha881]

I'm doing an oil change today b25 with oil cooler. The car has 10w40 semi in at the moment. I'm going to be using motul 5w40 fully synthetic. However I've just realised that the oil in the cooler will end up mixing with the new grade. What should I do? Is there a way to drain the cooler aswell?

[biffer]

apparently,cars that are driven normally never use the oil-cooler,it's only in extreme use such as driving on-track that the thermostat diverts oil through the cooler.
so for majority of these engines the cooler never gets any use,and might as well not be there.

[Gavt]

Not sure if mine has been fiddled with but i took off my cooler pipes and started the engine only to find it does get a supply of oil constantly as my my engine bay was covered

[paultv]

I may well be wrong, but according to oil spec - 5w40 is for seriously low temps, like -40C to -20.

I realise modern engines are designed to run on water thin oils - but the E30 was designated to use 15W40 or 20w40 in a Western European climate.

Bently states, "avoid driving on 5w or 20SAE oils at speed or if the indicated temperature rises" of course thats an American manual.

Anywhoo, I'm sure Brian will put me straight on this, probably synthetic is fine, gawd knows.

Paul

[Cloggy Saint]

I ditched the oil cooler on my car with no adverse effects. The M50/M52 doesn't have one so no real reason why an M20 would.

[biffer]

Not sure if mine has been fiddled with but i took off my cooler pipes and started the engine only to find it does get a supply of oil constantly as my my engine bay was covered

dunno then-i was parroting what i'd read on here in the past.

i'd owned and driven my 325 for a year before finding that the 2 cooler-pipe unions on filter housing were only hand-tight so that sort of supported what i'd read about the cooler being redundant most of the time. Maybe cooler-thermostat is faulty on your motor?

[tha881]

I had the part in the garage to ditch the cooler so decided to do that in the end as I didn't want old oil mixing with the new. I can always refit it in future. I've drained it as best I can but wondering if there is a way of doing it other than just letting gravity do the work?

Also, 5w40 fully synthetic is what Opie recommend

[Carmo13]

When I tried fully synthetic in my 325i, I found the engine used quite a lot of oil and I had to keep topping it up, so I ended up going back to semi.
My engine has done 140,000 for reference.
This may be bad advice but personally I wouldn't stress too much about mixing the oils.
Semi is a mix between mineral and fully synthetic anyway so they will mix with no problems in my eyes.

[DanThe]

Not sure if mine has been fiddled with but i took off my cooler pipes and started the engine only to find it does get a supply of oil constantly as my my engine bay was covered

dunno then-i was parroting what i'd read on here in the past.

i'd owned and driven my 325 for a year before finding that the 2 cooler-pipe unions on filter housing were only hand-tight so that sort of supported what i'd read about the cooler being redundant most of the time. Maybe cooler-thermostat is faulty on your motor?

There is a small, constant supply to the oil cooler, if there wasn't it would be full of air.
Easiest way to delete it is to remove the complete unit off the side of the block and fit the threaded adaptor from an M20B20 which the oil filter screws straight onto

[Brianmoooore]

Oil doesn't flow through the cooler in normal driving because a bypass valve is open, and the oil mostly takes the easier route. If you disconnect the cooler pipes, leaving them open, then onto the garge floor becomes the easier route.
5W40 fully synthetic is 100% suitable for your car, in spite of what the handbook says, since oils like this didn't exist when it was written.
There is no downside whatsoever in removing the oil cooler on any E30 325i, except on the most hard driven competition cars. As DanThe says, remove the adaptor block, and replace with the simple double ended bush used on the M20B20.