Recommended Oil After Rebuild???

[jwernquist]

Anyone know the best weight oil to use after a rebuild? 20-50 ?? 10-30??

ANyone?

PS: Motor in question is a 2.7!!

Thanks for any input you can provide!

Jon

[jwernquist]

ANyone Please?????

[Vintage911Racer]

My mechanic had me break it in with Castrol GTX 10-30 Non Synthetic.
Ran it for about an hours worth of track time and then changed it to 20-50

[Jim Sims]

20W50 natural oil until the "break-in" is done. Then switch to your long term oil; either natural oil or synthetic oil. 10W30 is too light for an aircooled engine in the summer. Cheers, Jim

[jwernquist]

Thanks guys thats what i needed!!

[Vintage911Racer]

Jim,

Why do you think 10 30 is too light???
To be honest with you, I have done some test at the track with 10W30 and 20W50. The 10W30 actually kept the car cooler. Why.... for a couple of reasons,

1) oil is not as thick, motor does not have to work as hard to get through it, (possibly mor HP, be it a small amount).
2) The "HOT" Oil actually drains off the moving parts quciker, allowing it to get back into the tank, out to the coolers and back into the motor.
Thus resulting in a cooler engine.

Now I would not reccomend running the 10W30 in tempratures in the high 90's or low 100's if this is a track car that revs to 8K every time.

But for every day driving use, I do not see a problem with keeping it in the car.

I have a buddy at Plavan Petroleum (he actually owns the company), he is an oil genius..(compared to me) but he says the 10W30 is fine until you start seeing ambient tempratures above 95'.

And the somewhat "New school" train of thought is that thinner is better.
I guess it is all up to the guy driving the car. What makes him sleep better at night.

[RoninLB]

I used straight 30w non-detergent dino

[Jim Sims]

The reason for the higher viscosity with natural (dino) oils is to ensure an adequate lubrication film in the journal bearings at higher summer temperatures. Heat transfer is only one of the two important functions of oil in a 911 engine and of course lubrication is the other. If there was no need for lubrication using water would be even better (much better) than light weight oil for removing heat. Before the infamous "synthetics only" Porsche oil recommendation; one of the previous official Porsche recommendations stated to use 20W50 oil in the summer (10W30 or 10W40 were not listed for summer use) in the engines of the earlier 911 cars. One should be also be cautious about the general temperature cutoff limits for when to switch oil grades as these could be based on water cooled engines which operate with more uniform engine temperatures. Cheers, Jim

[garibaldi]

Straight 40 weight, let it warm up and then go.

[Henry Schmidt]

Originally posted by garibaldi
Straight 40 weight, let it warm up and then go.

Absolutely, but be careful, cold 40w can blow up oil coolers.
Straight as opposed to multi-grades lubricate better.

[smestas]

If one uses a straight 30 or 40 weight is it just used for the initial 20min break in or is it used for the first few (0-500miles) oil changes?

[A Quiet Boom]

Originally posted by RoninLB
I used straight 30w non-detergent dino

I concur. Straight 30wt is just light enough to get pumped around easily yet heavy enough to protect the motor during breakin. Take it easy for the first 500-1000 miles then switch to your regular oil. I use 20w50 dino.

[RoninLB]

Originally posted by A Quiet Boom
I concur. Straight 30wt is just light enough to get pumped around easily yet heavy enough to protect the motor during breakin. Take it easy for the first 500-1000 miles then switch to your regular oil. I use 20w50 dino.

that was exactly my routine.. The gas pedal was constantly pumped between about a 500rpm band+ occasional 5k-6k blast. I never used 5th. It was all hy driving for an hour or two at a time. I got used to the head rocking from the pumping after appx 30mi. what a pisser.
oh, I broke the cams in for an hr on the same oil.