Charles,

Thanks for the hard work. I am sorry if I appear to have added to your load.

I have used the Castrol TWS 10w60 - it's great stuff.

Thanks for posting that info.

I had tested Castrol Syntec 5w50 and it was among the lowest in Zn and P, and had a TBN lower than most non-synthetics, just in case someone asks why it's not on the list above.

No, not at all. I enjoy doing it.

I knew I'd regret selling my cat test pipe! Went through the same problem with the DB4 on its recent rebuild. Went for the Shell Rotella T.

Looks like Rotella is being reformulated for 2007. Still a good Zn number, but in some forumlations P is lower than 0.12 ...

http://www.shell.com/static/ca-en/downloads/shell_for_businesses/oils_lubricants/rotella/rotella_comparisons.pdf

Thanks for all the great information everyone. Because I live on an Island with limited access to peformance dino oils the best I could find in my weekend hunt was Shell Rotella T - so that is what is it going to be for me. Sounds like others here are happy with it too. I almost decided to try a synthetic but came across an interesting comment in the Penrite guide for older cars (link provided by Knap: http://www.penrite.com.au/files/9R5...ILS_AND_API.pdf ) that suggests that "older engines" wont benefit from synthetics (regardless of their levels of ZDDP) unless an older engine has been reconditioned and correctly "run in".

[edited for manners...]
ps. Welcome to Pelican Knap, who are you? Do you like porsches or are you interested in oil or...?

well, the professional engineers at Porsche AG say to use a synthetic...

Help. The more information I see, the more confused I get.

I have a 1973.5 T, with about 100K on a rebuilt engine. It has never run on synthetic oil -- as far as I know.

I do not race.

Am I correct that the consensus is that any of these three dino oils will treat my engine well?

Pennzoil Racing Motor Oil 25W-50
Valvoline VR-1 20w-50
or
Shell Rotella T????

If not, please put me out of my misery and tell me what to use?

Thanks.

Depending on what oil temperatures you run and outside temperatures at which you run the car, I'd say Shell Rotella T would be fine as long as you have sufficient oil pressure at whatever the hottest temperature the oil runs. Secondly, depending on whether your guides and/or rings are worn or you see frequent high temperatures (no additional oil cooling), the VR-1 with it's added viscosity would be good. I have not been pleased with most of the Pennzoil and personally would not even use them in my lawnmower.

I think you mistakenly called Brad Penn Racing 20W50 a Pennzoil oil? Based on the information we've been given by the guys with the knowledge, Penn and Pennzoil are vastly different oil formulations.

Most definately, Brad Penn/ Penn Grade and Pennzoil are totally different products. The Brad Penn oil is made of pennsylvania crude in the same plant where the original kendall gt was made. God only knows what Pennzoil uses...

Thanks for clarifying!

Is this the good stuff?

http://www.powerservice.com/diesellube_oilextender.asp

Yup, it's meant for topping off your oil between changes, and boosts Zn, P, and detergents.

Would it be wise to add the "good stuff" when performing an oil change right from the get go as opposed to topping off only?

If you start with a good oil, there should be no need to add GM EOS or the Diesel Service Oil Extender at time of oil change. If you do add, just add enough to boost the levels to where they need to be. Too much isn't good either.

Well, I was interested in finding Diesel Service Oil Extender in northern California, so I went to their website and filled out the farm.

This is the reply I got:


Dear Chris:

Thank you for contacting Power Service Products, Inc. Diesel Lube Oil Extender is a product that has been discontinued and will not be replaced by another product. Power Service has chosen to focus on its core business - additives for diesel fuel.

I wish I had a better answer for you.

Please let me know if I can be of additional assistance.

Sincerely,

Mandy Storm



Now what? :(

I guess I am going to buy up what I can find.

GM EOS is still available but at it's relatively high price compared to the Diesel lube oil extender, it makes a poor top off oil (it also is very thick, like honey, which I am not a huge fan of).

Yeah. I'm going to visit the truck stops I know about on the way to our cabin.

Maybe the Brad Penn folks would like to take over production...

Hi guys, thanks for all this excellent info.

What do you think of this additive?

http://www.zddplus.com/