90's VW watercooled engine

[VMaxxor]

Hi,

I'm Bert from Belgium and recently the oil thing got to me.. (after blowing up a gearbox, that's another story, haha)

I'm currently running 10W40 semi synthetic in my 1.3 and I'm getting some comments about it from other VW enthusiasts.

Changed the oil yesterday and my pressures seems to be higher than before (same oil), so my guess is this semi syn oil gets thinner with age?

1.9bar at 1000rpm, 112C (27psi, 233F)
5.3bar at 3500rpm, 112C (76psi, 233F)

This engine has no oil cooler so the oil does get quite hot.
Before my oil change I used to get 1.2-1.4bar at idle (1000rpm).

My worries are about the pressure and flow. I looked at the datasheet for my oil and it says this oil gets 10cSt at 110C. So that's spot on, the only problem is that the oil relieve valve in my filter is at 6bar, so I run out of oil pressure at 4000rpm or so.

Should I switch up to 30grade oil? I'm worried about the temperature the 30 grade oil would be running, if the engine keeps getting up to 110C the oil would be too thin. Or not? The increased flow from the 30grade oil should cool down the engine, but by 10 degrees? I hope it does, a cooler engine would be welcome.

One of my VW mates is running the prescribed 20W-50 mineral, I guess his oil pressures are trough the roof? (No OP gauge). He comments that my oil is too thin, but the 10cSt at 110C seems to be spot on to me.

Great forum you guys got over here

Bert

 

[CATERHAM]

Welcome to BITOG!

Thanks for the great info which makes making a recommendation
fairly easy.
Do you know what the minimum oil pressure spec's are for your engine? If not I wouldn't run an oil that generates less than 4 bar at 4,000 rpm.
Did the used semi-syn 10W-40 still achieve this OP?
A fairly shear stable 30wt with a HTHS vis of at least 3.5cP should still provide adequate OP.

 

[VMaxxor]

Originally Posted By: CATERHAM
Welcome to BITOG!

Thanks for the great info which makes making a recommendation
fairly easy.
Do you know what the minimum oil pressure spec's are for your engine? If not I wouldn't run an oil that generates less than 4 bar at 4,000 rpm.
Did the used semi-syn 10W-40 still achieve this OP?
A fairly shear stable 30wt with a HTHS vis of at least 3.5cP should still provide adequate OP.


Thanks for the reply.

I know there are sensors that complain when oil pressure is under .5bar or under 1.8bar at 2000rpm and up.
My used oil gave me around 1.2bar/1000rpm, this, or 1bar/1000rpm is what I'm looking for.

Should I evaluate how long it takes for the oil pressure to drop? I do rev the engine up to 5500rpm now and then, so the high oil pressure bothers me right now.

I also wouldn't mind if 30wt oil brings the temperature down a bit, how is your experience with temp difference between oils?

Bert

 

[ericthepig]

I ran 20w50's in a Mazda GLC (1.5L I think) and a Mazda 323 (1.6L). Did it for years then compared to 10w40, and the 20w50's really seemed to bog the engine down in the comparison. Always had a love for them till I noted this. All this was back in the late 80's and early 90's when it was recommended - "run 20w50 in high revving cars".