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Oil .... how hot is too hot

Posted: Sun Jul 26, 2015 10:55 pm
by scrappy1382
since the front end rebuild i have been having a few issues with the oil temp, before it used to stay 95-98c max. coolant would be just over half.
now the oil keeps rising to a 115c :shock:
for me, this is way too hot for my liking, so,,,,, i searched for many hours on the tinternet , with people saying 115c is fine !
me personally what would normally cause the system to reach temperature that high ???? without air in system and new parts ( tested ) im kinda baffled on this one,
so please, as the title says, how hot is tooo hot ? before engine gives up that is

Re: Oil .... how hot is too hot

Posted: Mon Jul 27, 2015 12:02 am
by james butler
dont forget that oil gets to areas of the engine thats hotter than where water gets to.
as to how hot oil should get i have no idea but i would like to think that it should be close if not higher than the coolant temp.
i would have thought 115c would be ok seing as coolant under pressure has a higher boiling point and also the cut in point of most radiator fan switches is 95c.
for example
http://www.eurocarparts.com/ecp/c/Volks ... c68&000529
this is a two stage switch for hot and really bloody hot. the really hot is 92-102c so the fan would be kicking in properly by now and i would expect the oil to be at least a bit hotter than this in my opinion.

Re: Oil .... how hot is too hot

Posted: Mon Jul 27, 2015 9:14 am
by mark1gls
What sort of driving are you doing?
115 is Ok but it is hot for a VW engine, my golf with the water feed oil cooler runs at 90 in normal moving traffic and more on a motorway, the Mk1 Scirocco with no oil cooler will run about the same on normal driving but does run hotter on motorways, if I'm going a little over the speed limit and pushing it the oil will run towards the 120.

I would be looking to getting it running around the 90 to 100 in normal driving

What type of oil cooler are you using and what have you done to the engine?
Are you sure the oil temperature sender and gauge are OK?

Re: Oil .... how hot is too hot

Posted: Mon Jul 27, 2015 1:50 pm
by scrappy1382
mark1gls wrote:What sort of driving are you doing?

i tend not to take it easy :-D but saying that, i done a system flush ( late ) last night, and now temp is running with harsh driving 102, cruising 98.... oh, and replaced with the "blue coolant" ( how this made any difference i dunno ) but im happier with the results.
in relation to the oil cooler, its the original square style that the oil filter screws into, and new oil, super 2000 10/40 semi.
i will keep this updated after todays session in the car 8-)

Re: Oil .... how hot is too hot

Posted: Mon Jul 27, 2015 3:36 pm
by mark1gls
Glad it's come down a little, the coolant will make some difference to the oil temp as you have an water feed oil cooler so the hotter the water the hotter the oil.