Oil temperature
Discussion
Engine is a 500bhp 383 SBC. Just got around to fitting an oil temp gauge and, after a short drive out last night, it has confirmed that my engine oil is taking a LONG time to get anywhere near operating temperature. I was driving for about 15-20 mins and the oil temp didn't even reach 50C. I don't have an oil cooler.
My sump is a deep 7qt sump so, including the filter, I'm running about 8qts (9 litres). Now, I could run less oil (say 6qts/6.8 litres) and still be OK as the stock oil pans are 5qts. Presumably, this might help with getting the oil up to temp more quickly as there's less oil to absorb the heat from the engine?
Will going to a thinner oil have any effect on how quickly the oil heats up? I have plenty of oil pressure to permit a thinner oil to be used (currently running a 20w50 and thinking of going to a 10w30). Not sure whether the increased flow rate of the thinner oil will result in any difference in how quickly it gets up to temperature vs the increased resistance to flow of the thicker oil?
My sump is a deep 7qt sump so, including the filter, I'm running about 8qts (9 litres). Now, I could run less oil (say 6qts/6.8 litres) and still be OK as the stock oil pans are 5qts. Presumably, this might help with getting the oil up to temp more quickly as there's less oil to absorb the heat from the engine?
Will going to a thinner oil have any effect on how quickly the oil heats up? I have plenty of oil pressure to permit a thinner oil to be used (currently running a 20w50 and thinking of going to a 10w30). Not sure whether the increased flow rate of the thinner oil will result in any difference in how quickly it gets up to temperature vs the increased resistance to flow of the thicker oil?
20mins of light load/low rpm driving in a normal (<25degC) ambient will not be enough to get the oil up to temperature!
It can take over 30-40mins to get oil temp above 75degC without an oil/water heat exchanger.
Solution, drive faster....... ;-)
Also, if the temp sender is in the oil filter, this is quite a "cool" location, because it is sucking relatively cold oil from the bulk oil in the sump. The oil in the galleries will be hotter (as it upheats from the block/head oil ways, usually to the tune of 5-12degC.
It can take over 30-40mins to get oil temp above 75degC without an oil/water heat exchanger.
Solution, drive faster....... ;-)
Also, if the temp sender is in the oil filter, this is quite a "cool" location, because it is sucking relatively cold oil from the bulk oil in the sump. The oil in the galleries will be hotter (as it upheats from the block/head oil ways, usually to the tune of 5-12degC.
Max_Torque said:
20mins of light load/low rpm driving in a normal (<25degC) ambient will not be enough to get the oil up to temperature!
It can take over 30-40mins to get oil temp above 75degC without an oil/water heat exchanger.
Solution, drive faster....... ;-)
Hmm, so what do I do when I just want to take the car out for a QUICK blast? Don't wanna be pootling around for 30-40 mins until I can give it some beans! I'm gonna try filling with less oil (6qts vs 9qts) and see if that makes much difference.It can take over 30-40mins to get oil temp above 75degC without an oil/water heat exchanger.
Solution, drive faster....... ;-)
Will going to a thinner oil make any difference to the oil temp?
After the engine coolant is up to normal operating temperature, try using more engine rpm, this will heat the oil faster than driving at low rpm.
The only real issue with cold oil is when you never get the oil temp over 100degC, then the oil tends to retain a lot of water (from condensate), which would be boiled off. The cure for this is to change the oil more often.
If it is a real issue, then fitting a oil-water heat exchanger is the answer. (because the coolant circuit actually heats the oil circuit during warm up ;-)
The only real issue with cold oil is when you never get the oil temp over 100degC, then the oil tends to retain a lot of water (from condensate), which would be boiled off. The cure for this is to change the oil more often.
If it is a real issue, then fitting a oil-water heat exchanger is the answer. (because the coolant circuit actually heats the oil circuit during warm up ;-)
ian_uk1975 said:
Hmm, so what do I do when I just want to take the car out for a QUICK blast? Don't wanna be pootling around for 30-40 mins until I can give it some beans! I'm gonna try filling with less oil (6qts vs 9qts) and see if that makes much difference.
Will going to a thinner oil make any difference to the oil temp?
yes use a thinner oil it will circulate better if not get warmer it might even run cooler because of less drag !! the fastest way to warm it up is to run it at a fast idle with the car stationary But if it was me like the OP I would just change the oil more often use a basic semi syn 10/40 so it dosent cost a fortune cool oil wont hurt as long as the rest of the engine is up to temp esp if you run a thinner oil ...Will going to a thinner oil make any difference to the oil temp?
Less oil is a much better way forward than changing grade: oil grade shouldn't be changed unless you have made significant changes to the oil system, such as higher displacement pump or wider/more galleries.
Oil grade is chosen to get the desired oil pressure when flowing a given displacement through a given orifice (or combination or orifices). Lowering your oil grade will reduce the oil pressure you have and this can starve some parts of the engine of oil (lower pressure will mean that squirt jets earlier in the oil system will deliver proportionally more oil than those later in the system).
I wouldn't change oil grade unless you absolutely have to, and taking too long to warm up is not absolute having to in my opinion.
Oil grade is chosen to get the desired oil pressure when flowing a given displacement through a given orifice (or combination or orifices). Lowering your oil grade will reduce the oil pressure you have and this can starve some parts of the engine of oil (lower pressure will mean that squirt jets earlier in the oil system will deliver proportionally more oil than those later in the system).
I wouldn't change oil grade unless you absolutely have to, and taking too long to warm up is not absolute having to in my opinion.
Nick3point2 said:
Less oil is a much better way forward than changing grade: oil grade shouldn't be changed unless you have made significant changes to the oil system, such as higher displacement pump or wider/more galleries.
Oil grade is chosen to get the desired oil pressure when flowing a given displacement through a given orifice (or combination or orifices). Lowering your oil grade will reduce the oil pressure you have and this can starve some parts of the engine of oil (lower pressure will mean that squirt jets earlier in the oil system will deliver proportionally more oil than those later in the system).
I wouldn't change oil grade unless you absolutely have to, and taking too long to warm up is not absolute having to in my opinion.
Well, in my case, I was getting rather high oil pressure with 15w50... this is a fresh engine with very healthy bearing clearances. I'm also using a high volume pump, which also ups the pressure a tad. I've now switched to a 10w30 since I posted this thread and my hot oil pressure is virtually identical (within 1-2PSI) to what it was with the 15w50!Oil grade is chosen to get the desired oil pressure when flowing a given displacement through a given orifice (or combination or orifices). Lowering your oil grade will reduce the oil pressure you have and this can starve some parts of the engine of oil (lower pressure will mean that squirt jets earlier in the oil system will deliver proportionally more oil than those later in the system).
I wouldn't change oil grade unless you absolutely have to, and taking too long to warm up is not absolute having to in my opinion.
Max_Torque said:
After the engine coolant is up to normal operating temperature, try using more engine rpm, this will heat the oil faster than driving at low rpm.
The only real issue with cold oil is when you never get the oil temp over 100degC, then the oil tends to retain a lot of water (from condensate), which would be boiled off. The cure for this is to change the oil more often.
If it is a real issue, then fitting a oil-water heat exchanger is the answer. (because the coolant circuit actually heats the oil circuit during warm up ;-)
You could also add a coolant pre-heater and electric oil pump in at the same time (Kenlowe hotstart or similar) and effectively pre-heat the oil before you even start the engine...The only real issue with cold oil is when you never get the oil temp over 100degC, then the oil tends to retain a lot of water (from condensate), which would be boiled off. The cure for this is to change the oil more often.
If it is a real issue, then fitting a oil-water heat exchanger is the answer. (because the coolant circuit actually heats the oil circuit during warm up ;-)
Or bypass that entirely and put a small electric heating element in the sump? (Mains powered)
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