Oil temperatures

[matt-me]

Out of interest what consensus temperature should you be able to hold the dipstick at? 85-100/110'C is chuffing hot...I know it's momentary but still, you'll burn..

I'm just saying that 75-80'C is probably holdable but after that, when it's not, people still have a range to go rather than totally panic they are frying their engine..is that fair to say?

I have a temp gauge, but I still do the dipstick test out of interest. On a run (not necessarily in this weather), the gauge is reading 85'C, I have a longer 4th gear, and this is around 3500 rpm. Allowing for my gauge to be a little inaccurate, the dipstick is probably too hot to hold for any length of time.

What do people think?

 

[atafonso]

The dipstick holding is just a guide, one cannot hold a piece of steel at 85deg C for too long, so if you can touch it for a few moments then it's not too hot. The best way is really a good gauge connected to either the sump plug or even better, the place where the type 3 cases have the oil dipstick tube.

Abel

 

[matt-me]

Useful Abel, thanks

 

[mike.s]

Currently in France - 35 degrees in the shade...

Cruising a 65 ish for an hour or two and temps starting to hit 100/105 - on a hill I have to drop to 55 to keep temps down.

Never known it so hot in my life so probably exceptional circumstances!

Have loads more power there aswell which I can't use in these temps but would rather keep the temps down if possible.

Oh that's a 1915 with an external oil cooler aswell although no ducting just angled into air flow. Vdo sensor mounted in oil filter head on route back to engine.

6 rib gearbox so rpm about 3000rpm ish
6

 

[Rhodrich]

According to VW, temperatures up to 120 degrees are acceptable on a highway run....

It may seem counter intuitive, but your engine will run cooler with a 30 weight oil than a 50 weight oil. This is because the oil cooling system works on a pressure basis, rather than temperature, and is designed to work with a 30 weight oil. It interprets high pressure as being cold, and low pressure as being hot. If you use a heavier weight oil, this gives you higher oil pressure, and oil is diverted away from the oil cooler, so it runs hotter. See here for the details....
https://www.thesamba.com/vw/forum/viewtopic.php?t=280293

I would recommend a straight 30 weight oil or a 15w40 multigrade.

 

[mike.s]

That's quite interesting - do you know what pressure the valve to the oil cooler opens at and also what pressure it is fully open at?

 

[Rhodrich]

It's not quite that simple. The response to oil pressure is not linear. It opens at a much higher pressure than it closes at. It's all very clever! Have a good read of the thread I posted a link to.

 

[atafonso]

The absolute max temp you want your engine to run is 120 deg C. After that, oil quickly oxidizes and stops lubricating. As you can see, at 270 deg F or 132 deg C, it already lubricates only 55%.
I normally suggest when you see a temp of 110 and it is rising, look for a place to stop as you don't want to let it hit 120 for it will start damaging your engine. If it hits that high it has a cooling or building problem anyway that needs to be looked at.

Abel

 

[atafonso]

That's quite interesting - do you know what pressure the valve to the oil cooler opens at and also what pressure it is fully open at?

Mike, if all is according to VW specs, the valve should open at about 60 psi and close at about 25 psi.
Just a thought, on the newer Brazilian cases, the relief oil control gallery passage width is 10mm and not 6mm like the older cases, so if you want to use a 30mm pump it is perfectly acceptable. In fact, VW has made this mod when they themselves used a 30mm filter pump on the Mexi Beetles.

Abel