Oil temperature. Something new to worry about?

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CalicoJack

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On the boat we have a Perkins 4108, which starts and runs very happily, but even after running for several hours the temperature of the oil remains no more than hand hot; this is scientifically measured by grasping the oil filter and saying, um, that’s not very hot. The oil in our case does go through an oil cooler, which is clearly doing its job.

This week I have brought a new car, which has amongst other things a setting where it tells you the oil temperature. I was worried to find that the gauge was reading over 105 degrees Centigrade. At the time we were driving on the motorway at 70mph and had been for sometime. As the temperature of the oil didn’t get any higher I assume that this is acceptable; certainly none of the warning lights, of which there are numerous came on. Subsequently I have checked this from cold, and it doesn’t even register until it gets to 50 degrees C.

Question, is the Perkins running too cold, or is the car just one of these new dangled things that does things differently?
 
Completely different engine, but the oil filter on my VP 2002 gets to about 75-80C after many hours of running.
It is actually the hottest part i've found (so far) of the engine, except for the exhaust elbow just before the water jacket.
 
Was the engine running under load, or just idling?
I would think it preferable that the oil gets 'fairly hot', as it gets rid of water from the oil.
As your engine has an oil cooler, presumably there is heat to be got rid of when the engine is working hard.
 
Yes, I meant working under load. I was thinking of the trip we did from Harwich down to the Medway, where there was not a breath of wind, and the engine ran for perhaps five hours at 2,000rpm.
 
CalicoJack said:
Yes, I meant working under load. I was thinking of the trip we did from Harwich down to the Medway, where there was not a breath of wind, and the engine ran for perhaps five hours at 2,000rpm.
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Just like a Sunday afternoon stroll, then! Why do you think you might have an oil temperature problem? Will only occur if something fails and you will get plenty of warning through water overheating first.

Nothing to be gained from trying to compare your ancient engine with today's high performance engines. At 2000 your engine is producing somewhere around 25hp compared with between 2 and 3 times that for a modern engine at the same revs.
 
The OP's question illustrates perfectly the need for synthetic lubricants in cars but not in boats. At a constant 105C the heavy ends in a distillate lubricant are carburising, causing deposition of sludge in the oil and lacquers on hot surfaces. And that is in winter, presumably it is even hotter in summer. There are no heavy ends in synthetic lubricants, so the oil does not form such deposits. At 50C a synthetic lubricant is overkill, totally unnecessary for the conditions. Plus of course, the TBN of an oil intended for high temperature operation is quite high, which may well cause medium term wear problems in a cool engine.
 
vyv_cox said:
The OP's question illustrates perfectly the need for synthetic lubricants in cars but not in boats. At a constant 105C the heavy ends in a distillate lubricant are carburising, causing deposition of sludge in the oil and lacquers on hot surfaces. And that is in winter, presumably it is even hotter in summer. There are no heavy ends in synthetic lubricants, so the oil does not form such deposits. At 50C a synthetic lubricant is overkill, totally unnecessary for the conditions. Plus of course, the TBN of an oil intended for high temperature operation is quite high, which may well cause medium term wear problems in a cool engine.
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That's very naughty of you to sneak that one in Vyv, knowing full well that it might well also illustrate that if you can afford to use a suitable viscosity grade of synthetic lubricant in a boat engine then because of the much lower oil degradation rate you will be able to leave the oil longer between oil changes and the TBN will guard against any acidic build up damaging the engine during the extended periods of non-use in winter. In fact, financially speaking, rather than overkill it might well actually prove more cost-effective. :)

But is this debate not one of the mainstay joys of the Forum? ;)

Richard
 
vyv_cox said:
All oils have a TBN. The question is what damage is an excessively high one doing? The TBN is low in oils intended for a cool-running engine quite deliberately.
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I understand that .... but there is no evidence that the TBN of a typical i/c synthetic oil is doing damage at least sufficient to outweigh the improved and more long-lived lubrication qualities of synthetic oil. :)

Richard
 
Thanks for the TBN discussion - I hadn't come across it before. Google suggests a low TBN oil is OK for the low sulphur fuel generally available in Europe. Is that a sensible conclusion?
 
The oil cooler referred to is presumably a matrix of engine coolant and engine oil. So in effect an oil warmer and cooler keeping oil same temp as coolant. olewill
 
RichardS said:
That's very naughty of you to sneak that one in Vyv, knowing full well that it might well also illustrate that if you can afford to use a suitable viscosity grade of synthetic lubricant in a boat engine then because of the much lower oil degradation rate you will be able to leave the oil longer between oil changes and the TBN will guard against any acidic build up damaging the engine during the extended periods of non-use in winter. In fact, financially speaking, rather than overkill it might well actually prove more cost-effective. :)

But is this debate not one of the mainstay joys of the Forum? ;)

Richard
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One of the causes of falling TBN in oil is running at low temperature, which encourages acids to condense on the cylinder walls.
Slow running at light load is prone to using up the TBN additives quickly.
 
lw395 said:
One of the causes of falling TBN in oil is running at low temperature, which encourages acids to condense on the cylinder walls.
Slow running at light load is prone to using up the TBN additives quickly.
Click to expand...

So you're saying that engines that run slowly at light load, like marine engines, are better off starting with a high TBN so there is plenty of scope for neutralising the acidic condensate?

Richard
 
RichardS said:
So you're saying that engines that run slowly at light load, like marine engines, are better off starting with a high TBN so there is plenty of scope for neutralising the acidic condensate?

Richard
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I would start by looking at the thermostat, then maybe go a bit faster to make sure the oil warms up.
 
The engine either has a duff thermostat or needs to do more work to heat up.
Driving a boat faster is more work. The prop will need more torque at 2500rpm than 2000 rpm.
 
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