Engine Oil

[cabtone]

My Mistral is prone to overheating when towing. It's not so bad now I've replaced the pump, stat, rad cap, and flushed the cooling system. I've also reverse flushed the radiator.
Now I'm thinking, I wonder if the type of oil you use could make any difference. Last oil change I used 10w 40 semi-synthetic (I think). Maybe I should go back to 15w 40 mineral, which I see is recomended. Maybe using a thicker oil is better when towing. I'm no expert.
Anyone got any thoughts on this one?

 

[clivvy]

i think under load, the oil will make a big difference-the more the engine struggles, the hotter it will get, this heat will then just wear everything out more.might be worth considering an electric fan if it gets bad...

 

[macabethiel]

oils etc

I do not think the grade of oil will make any difference as the thermal capacity of the oils will be very similar whatever the grade.

A synthetic oil will take more heat before it breaks down than a mineral oil so will hold onto its lubricating ability better.

As said by previous post an upgraded fan will help as would an oil cooler.

 

[BigBlack]

How much weight are you towing???
Is the car fine otherwise?
When you say overheating do you mean sat at side of road with steam coming out of the bonnet, or just your temp gauge rising? :nenau

 

[Timbo_1975]

The official spec for oil in the TD27 is 10w-40 for all temps we're gunna normally experience in the UK. A thicker oil will take the edge off mpg a touch, and may affect cold starts when its really cold due to the drag.

Your overheating issue will not be caused by the oil grade.

Have you checked that it is actually overheating - thermometer in the header tank, and that the viscous fan clutch is definately locking up when hot? Is the rad cap able to hold the system at pressure? Stat fully open is at 88deg C usually.

Is your mistral an auto? Is the trans cooler trying to dump excess heat cos the converter isnt locking up?

After that, if you are CERTAIN that it is running hot, check the pump timing; if it is mechanical you can check easily, if its fly-by wire, then your needle lift sensor is operable.

That said, i think you will be waaaay down on power if the pump timing was so far retarded as to cause overheating.

Abit more info needed really, as to when it overheats, what sort of driving, does it loose coolant, and how long it takes to cool off etc.