Carpokes Porsche Forum

Looking for a concise straightforward answer to an incredibly complex question... What engine oil do you recommend I use in my stock, non-track, 951 ? Living in IL, I will start it and let it run often, but the car does not leave the garage during the harsh winters. I have been using conventional Penzoil 10w30 since I got the vehicle 8 years ago, but now that I am almost done with the engine resealing, and re-gasketing, Looking for possibly a better alternative. Thanks !!

Most commonly used with our flat tappet engines is Castrol GTX or Valvoline VR-1. High zinc content is the main priority though. I personally run valvoline VR-1 20W50 in my 2.5L.

As concise as I can be: you want something with a higher zinc (ZDDP) content to protect the cam and flat lifters; and either 10w40, 10w50, 15w50 or 20w50. Valvoline VR1 20w50 is a popular choice that checks all the boxes. If the motor is vulnerable to leaks, mineral oil tends to leak less in my experience. I recently switched to the new Motul mineral (dino) oil marketed to older cars:

Im a huge fan of LiquiMoly 10W40 MoS2.

I have used this oil in all of my classic/euro cars and it always makes them run much quieter and as Tom said, I have seen a motor with random 10w50 leave oil spots, switch to this oil, still leaks, but no significant spots on the ground. Less loss when checking the dipstick.

I personally would NOT start it and let it run a while . Idling in the cold is one of the worst things you can do . Either drive it or fully winterize it and wait until spring to drive it .

Poorsche44 wrote: Wed Nov 19, 2025 9:42 am Most commonly used with our flat tappet engines is Castrol GTX or Valvoline VR-1. High zinc content is the main priority though. I personally run valvoline VR-1 20W50 in my 2.5L.

Casrtol GTX is no longer high in zddp -- actually on the low end with 610ppm. They now have Castrol Classic GTX, however, with 1310ppm (per google). Here's a nice list of some high-zddp oils, courtesy of ChatGPT:

AMSOIL Z-ROD 10W-30/20W-50, ~1430 ppm ZDDP
Valvoline VR1 Racing (conventional), ~1400-1500 ppm ZDDP
Motul Classic Performance 20W-50, >1800 ppm ZDDP
Lucas Hot Rod & Classic 10W-40/20W-50, ~2100 ppm ZDDP
Driven Racing Oil HR Series, ~1600 ppm ZDDP
Mobil 1 Extended Performance 5W-30, ~900 ppm ZDDP
Castrol GTX Classic 20W-50, ~1400 ppm ZDDP
Pennzoil High Mileage 10W-40, ~800-900 ppm ZDDP
Shell Rotella T4 15W-40, ~1200-1400 ppm ZDDP
Shell Rotella T6 5W-40, ~1100-1200 ppm ZDDP
Summit Racing High-ZDDP 10W-40, ~1500 ppm ZDDP

996C438 wrote: Wed Nov 19, 2025 11:01 am I personally would NOT start it and let it run a while . Idling in the cold is one of the worst things you can do . Either drive it or fully winterize it and wait until spring to drive it .

Ok... So you bring up a completely different subject that I also have so many questions about !! If anyone has the time, can you please elaborate on what exactly I need to do to "winterize" a 951 ?

Unfortunately there is no possible way for me to drive the car in the winter around here. Way too much snow and salt on the road during our winters. I was under the impression that starting it and letting it run a while was a good practice. Can anyone chime in on what I should be doing instead ? Thanks in advance !!

Here's roughly the scenario . Put the fuel stabilizer of choice in the tank when you are at the pump . Then fill the tank . Drive for 15-20 minutes to get the mix into the injectors.

While hot/warm change oil and filter . Drive for 10-15 minutes to get it up to temp and drive it into your garage . Next air up the tires , I generally go 4-5 psi over normal pressures .

If rodents are an issue there are plenty of home remedies out there like moth balls as an example . You want to protect under the hood ( wires ) and the interior . Finally hook up a battery maintainer .

That's pretty much it . Come spring time she should fire up and be ready to go . Remove rodent deterants and adjust tire pressures . Take it easy for a few miles as tires will be flat spotted from sitting . Then let her rip .

RedMeanzGo wrote: Wed Nov 19, 2025 8:54 am Looking for a concise straightforward answer to an incredibly complex question... What engine oil do you recommend I use in my stock, non-track, 951 ? Living in IL, I will start it and let it run often, but the car does not leave the garage during the harsh winters. I have been using conventional Penzoil 10w30 since I got the vehicle 8 years ago, but now that I am almost done with the engine resealing, and re-gasketing, Looking for possibly a better alternative. Thanks !!

For a stock 951 in your climate, a good quality 15w-50 synthetic is the way to go. It protects the turbo and works for the driving you do.
Brands like Mobil 1, Liqui Moly, or Castrol Edge are all excellent choices. Stick with that weight, and you'll be golden.

Tom is spot on with the comments on high zinc content and though many of the high quality full synthetic oils out there are fantastic for new cars, the high zinc issue is an area you should focus on. Coming from a longtime track rat I would say you probably would not need a 50W, though it won't hurt, but since you do not track your Porsche I would suggest a 0-40W or 5-40 weight would be fine for the Turbo and weather in the Midwest. I do suggest a 50W for some of the students I have for NASA, SCCA or PCA DE events, so if you are considering in the future that is a good move.