Jim Chambers

Did a search and found the following:
WSM says use 75/90W gear oil
Wally/Porsche say use motor oil (15/40W ?)
Mrmerlin strongly urges STP/Visine bottle

I am doing my first ever TB re-tension and tensioner oil fill. I tend to be conservative and do what the manufacturer recommends, but not even sure what that is. And if STP is preferred over manuf. rec., why? Thanks

WallyP

The oil in the tensioner serves three purposes:
- Heat transfer from the block to the bimetallic washers, to prevent an increase in belt tension as the aluminum engine expands more than the belt as they get hot.
- Lubrication of the tensioner as it moves due to belt fluctuations and temp correction.
- Damping of movement due to belt fluctuations.

The earlier tensioners with no fill nipples used gear oil. The later tensioners should, according to Porsche, use engine oil. There isn't much difference between gear oil and engine oil in this application.

While I haven't talked to Stan about his recommendation and don't want to speak for him, my assumption has been that he is trying to increase the dampening effect and reduce any leakage...

I just go with the Porsche recommendations on my cars - YMMV.

Jim Chambers

Thank you. That is what I needed. Assume an ordinary pump oil can will work to fill.

mark kibort

use green or different color gear oil, that way, if it leaks, you can recognize it as coming from that area, not the engine.

Bill Ball

I kinda like Kibort's color idea. My car has had a chronic oil leak from the tensioner area even after several tensioner rebuilds with different methods of sealing the gasket and bolts (sealant is called for by the WSM on one of the upper tensioner mounting bolts). I can't see any oil above the tensioner, say, from the camshaft seal, but using some Kendall green to fill the tensioner would help to locate the leak to the tensioner. On the other hand, I do have a Porkensioner sitting on my parts shelf that would eliminate that source.

ROG100

Use Royal Purple and you will see the leak - 8>)

soontobered84

I just used Stan's reccommendation of STP and I have to say that I think that could be a real winner. It is thick ( thicker than 90W gear lube and smells SO much better. It is clear so it won't help find any leaks, but I gotta think that it also won't ooze out so readily as regular oil or gear lube.
I used a push tube case from a used up glue dispenser to fill mine as I didn't have a empty visine bottle.

SeanR

After talking with Stan after OCIC, I did the switch to STP and am very happy with it. I use a trigger oil can to fill with.

Mrmerlin

I will say this agian if your using the STP oil to fill your tensioner you will find that it wont leak near as quick as any other oil.
I also suggest to use a visene bottle with the tip drilled out a bit so the oil will flow, the reasons for this are 2 fold.
One it is very easy to refill the tensioner as the tip of the bottle neatly fits into the fill hole ( remove both nipples from the tensioner) and fits between the belts and radiator, a can is a bulky unit.( and can cause lots of extra RnR time)

Second it is actually quite easy to over pressure the tensioner with a hand pump unit, then the weak link is the inner sealing camp on the rubber boot,
an oil can will neatly blow this seal off then the tensioner has to be taken apart to reinstall the seal not to mention cleaning up all of the spilled oil.
I have done this once and dont want to repeat it so BTDT

Jim Chambers

Clearly you and others are pleased with the STP. I remember adding it to the crankcase of flathead Fords in the 50's to reduce oil burning. It is thick stuff! My fear (probably unfounded) is that it could be too thick and impact the operation of the tensioner in a negative way. Motor oil is way less viscous than STP. I guess I need to see if I have a leak problem to begin with. The front of my engine is very clean but that is from a detailing by the dealer.

Mrmerlin

after you put some miles /heat cycles on the engine then you will see the motor oil wetting the front underside of the tensioner, if you use the STP it takes a long time to see any tell tales

GregBBRD

So, other than being slower to leak out, what is the advantage of using STP?

jon928se

I suspect the most practical aspect of STP is it's thickness. If I knew what a Visene bottle is I would no doubt use one.

I do object to perpetuating the myth that the there is any serious damping function in the OEM tensioner.Go check out Tony Harkins web with it's diagram of the tensioner and then figure out wihich bits move when the belt tries to move the tensioner and which bits are damped by the oil.

GlenL

I'll squirt in whatever is in the oil can. Handy with the pump-fill action. Usually 10w40 or 20w50 in there.

As you can see in the chart, gear oil is not radically thicker than engine oil despite the differences in the numbers. Use whatever you like, really. Thicker oil will ooze out more slowly, but it's not going to cause it to seal up.

Am I the only guy to re-build the tensioner without removing it from the block? That's another way to avoid leaks.

Gary Knox

I recently did a timing belt replacement on my '89 S4 and since the tensioner had been leaking, re-did the gasket and refilled it. Still leaked!! I used Stan's procedure and found a small amount of seepage. I then made a mixture of about 15% "oil stop leak" additive from the local supply shop and 85% STP. After thorough mixing, I filled the tensioner with this. I haven't driven the car much, but it "seems" that the seepage has been significantly reduced, or maybe even stopped.
Gary Knox