Which oil thermostat switch the 82 degrees C or the 91C

TDH888 · 08-10-2017, 07:42 PM

Thanks to one of our Pelican member , he provided me the part no. of the BMW thermostat w/ different temp ranges. I narrowed it down between 82 and 91 degrees C. This is w/ regards to the thermostat switch for the fan of my oil cooler . The original thermostat switch is set at 110 degrees C . The car is an 89 930. I'm based here in the Philippines it's very hot and humid .

Thanks in advance ,

tdh888

Jeff NJ · 08-10-2017, 09:13 PM

How did it run with the original switch? If the car was able to handle the heat with 110, I see no reason to go all the way down to 82, and 91 is the better option. However, you need to make sure the oil and engine get up to temp and if it opens too early, it may take longer, or not make it at all. I have to assume that Porsche chose 110C for the switch because they want it to get that hot. If it works too well, it will never hit 200F+, which I think is where Porsche expects it to hit. Of course, your ambient temps there would affect this too, so you may be fine, whereas someone in Canada would have an issue with a lower temp switch.

Has anyone run the 91 C switch?

TDH888 · 08-11-2017, 12:20 AM

Thank you very much Jeff for your reply . Because of our weather ( heat & humidity) , when the car is stuck in traffic the oil temp gauge would go up to the third line and when it does the fan kicks in and the temp goes down a little bit then the oil cooler fan shuts down . Then this process repeats once the engine hits the 3rd line . This usually happens when the car is stuck in traffic w/ the AC on . The car's idling and performance is not affected at all when it's on the 3rd line of the temp gauge and goes down to the midway between the 2nd & 3rd line when it hits the open hi way. I was concerned because of the traffic problem we have in our country that because of the high operating temperature it might damage the engine in the long run . I just wanted to install a manual override but I wanted it to be stock looking interior w/ o an additional switch. So I read in the forum one can use a BMW thermostat switch , except that it has 2 poles instead of a single pole .
My sister who also drives an 89 930 Cab is based in Northern NJ .

Jeff NJ · 08-11-2017, 08:06 AM

Wow, that is hot and I would think that you wouldn't have a problem with the 91C switch in that case, especially since it is just the fan, not the Tstat that you are turning on early. Have you considered adding a front mounted oil cooler? A bunch of guys here have done that with excellent results. That way, once it does get up to temp, the two combined coolers can keep the car well within operating range. There's a bunch of threads here of people adding them.

TDH888 · 08-11-2017, 08:51 PM

Hi Jeff ,

Thanks for the reply , as much as I want to install a center mounted oil cooler I want my retain my stock car's appearance, thats why I opted for the lower setting oil thermostat switch .
Is it hard to dismount the original oil cooler from its position in front fender in order to access the thermostat switch ? I followed your advise and ordered the 91 degrees C thermostat.

Tdh888