Engine oil temp - TJ

I don't know what the temperature ought to be, but the trend sounds like what I would expect.

At low RPM's I would expect the engine oil to be about the same temperature as the engine coolant. However, at high RPM's (highway driving), I would expect the temperature of the oil to be higher. The difference is because an engine depends on heat conduction to lower the temperature of the oil. At higher engine speeds the heat transfer to the oil is higher than at an idle speed.

I had installed an engine oil temperature gauge on my TJ (using a filter sandwich plate). Results are as under:

• city driving at around 50 kms/hr - temp takes about 6-8 kms to rise above

• highway driving early morning at 100 kms/hr - temp takes about 15-20 kms to rise above 175F and then stays at 200F

• highway driving for a while (50+ kms) during the day followed by city driving (without stopping for cool down) in heavy traffic for 10 minutes - temp almost shot up to 215/220F. This came down a little as I started driving at city speed in better traffic.

In all above conditions, the engine coolant gauge (factory) stayed at 95C (about 195/200F). Coolant gets hotter quicker, but stays the same (so no cooling problems). Also, its winter in NZ.

Has anybody else got any insight into engine oil temp norms. Would this be normal behaviour. I have not had a chance to try it out in off-road conditions yet.

Thanks TW

Oil should be at least 215F to drive off the water and unburnt gasoline that are a natural part of blowby gases. Same reason you change the oil more often in an engine that is only used for short trips (never warms up). On the high side 230F would not bother me.

I am not worried at this stage. It was just an experiment to see what = was going on with the oil.

I drove in the city relatively aggressively today and it made no = difference to the oil temperature behaviour. Might have to go off-road = this weekend and see what happens.

Thanks TW

what I would expect.

At low RPM's I would expect the engine oil to be about the same = temperature=20 as the engine coolant. However, at high RPM's (highway driving), I = would=20 expect the temperature of the oil to be higher. The difference is = because=20 an engine depends on heat conduction to lower the temperature of the = oil.=20 At higher engine speeds the heat transfer to the oil is higher than at = an=20 idle speed.

I understood the concept and the reason, this just validates it for me = as a fact.

Besides, I can keep an eye on things to ensure that I do run it long = enough more frequently to bring it upto full temperature. Just using = the coolant gauge gave me false sense of engine reaching at "normal = operating temperature". It takes a lot longer than what I had always = believed to be. Same reason now I understand that the transmission = would take 20/30 kms before it gets hot enough to be in optimal = temperature zone. I have to hook up my trans temp gauge this weekend.

TW

--=20 jeff

Another reason I can tell my wife, that it is good that we live in the mountains! It will make her car warm up better and last longer. I knew there was a reason I wanted to live with all these hicks.

I live in a small town in the San Juan Mountains, fifty miles from a decent grocery store. I guess this is going to keep my Jeep running forever. Other people here, drive three blocks to the Post Office.

Earle

Besides, I can keep an eye on things to ensure that I do run it long enough more frequently to bring it upto full temperature. Just using the coolant gauge gave me false sense of engine reaching at "normal operating temperature". It takes a lot longer than what I had always believed to be. Same reason now I understand that the transmission would take 20/30 kms before it gets hot enough to be in optimal temperature zone. I have to hook up my trans temp gauge this weekend.

TW

-- jeff