Not sure what oil to run in Porsche 928 16v.

[Hethaerto]

I'm looking for a good oil for my '82 Porsche 928 4.5 V8 16 valve with flat-tappets.

The car's had a diet of Castrol GTX 20W-50 for several years, so the engine is heavily varnished now, and the owner before that owner ran 20W-50 as well, but I don't recall the brand. I think it may have been Swepco.

I'm thinking the heavy 20W-50 is serious overkill because the engine never really gets a good workout around here in Va Beach. Redlines at 6500, but the tach never gets over 2500.

I'd like to step it down to a 10W-30 or lighter, but I'm worried about not getting enough Zinc.

I want to use a lighter oil because I think the heavy stuff really bogs the engine down and robs economy, too. Right now I've got PP 15W-50 plus a bottle of Lucas Zinc additive.

I can almost watch my gas gauge needle move as I poke around town.

I also want to run ARX, but I want to run it with the best synthetic I can that won't counteract ARX's cleaning abilities. Frank says that Amsoil XL line will work, but I'll probably need to add some Zinc to it.

Any thoughts?

 

[addyguy]

If you can find it, Brad-Penn 'Penngrade 1' oils have lots of Zinc in them.

Outside of that, ANY 15W-40 HDEO will probably work well.

 

[zddp77]

addyguy got it right 15w40 as in Delo 400 , Rotella T ,Valvoline All Fleet. Dont run a full synthetic if these gaskets are original you will have major leaks. Forget the Auto RX you will be wasting your money.

 

[mechanicx]

Generally a 4-valve valvetrain wouldn't need as much ZDDP as a 2-valve since the valves are smaller, lighter valve springs and no rocker multiplication. 20W50 seems too thick. Since you want to do some cleaning and to play it safe Rotella 10W30, 5W40 or even 15W40 would be a economical and good choice.

 

[Audi Junkie]

Rotella 10w-30 or Valvoline ZR1, maybe Mobil 1 Hi-Miles would be best.

ARX is fine w/anything other than Hi-Miles oil or ester oil.

Rotella + ARX would be ideal. I run it a normal full oci.

 

[aquariuscsm]

If it`s one of those engines that specs a 20W50 and you need high zinc,how about a 20W50 racing oil?

 

[mechtech2]

Lots of good advice above - I like the 15-40 HDEOs as a good choice.
You are not doing yourself or the engine any favors with keeping it at 2500 RPMs and under. She has to see 4-5,000 here and there.
Also, remember that fuel has no lead in it anymore.
A lead substitute is a possibility, but cheap and common Marvel Mystery Oil helps with valve seats and other things with modern no lead[valve seat erosion in older cars] and alcohol infused fuels.

 

[Hethaerto]

Thing is, Porsche doesn't spec 20W-50, except for high heat regions. 928 enthusiasts think that the heavy oil is best, but it just doesn't make sense.

Porsche specs oil grades just like everyone else, based on regional temps. I don't live in Death Valley.

I'm putting in Amsoil XL 10W-30 right now, with ARX, and will monitor. When I feel the engine is cleaned out, I plan to upgrade to a high Zinc formula, but likely a mid-grade weight. I don't race the car, and it really doesn't break a sweat here in Va Beach.

Thanks for the feedback everyone. Rotella sounds interesting for the next OCI.

 

[Johnny]

Shell Rotella T (T6) 5W-40 Synthetic. That would fill all your needs, including the ARX usage if that is the route you want to go.

 

[Hethaerto]

Originally Posted By: mechtech2
Lots of good advice above - I like the 15-40 HDEOs as a good choice.
You are not doing yourself or the engine any favors with keeping it at 2500 RPMs and under. She has to see 4-5,000 here and there.
Also, remember that fuel has no lead in it anymore.
A lead substitute is a possibility, but cheap and common Marvel Mystery Oil helps with valve seats and other things with modern no lead[valve seat erosion in older cars] and alcohol infused fuels.


The car is spec'd for unleaded, and it does enjoy MMO in the tank.

 

[ryan2022]

I would stick to a 40 weight in that car.

I'd probably lean to an HDEO 10 or 15w40 and call it a day.

Great car by the way. My wifes aunt has an 86. tough as nails, and still a well balanced and powerful car by todays standards.

 

[Johnny]

What we really need is a picture of that beauty.

 

[Hethaerto]

Originally Posted By: ryan2022
I would stick to a 40 weight in that car.

I'd probably lean to an HDEO 10 or 15w40 and call it a day.

Great car by the way. My wifes aunt has an 86. tough as nails, and still a well balanced and powerful car by todays standards.


I've had it six weeks, have been slowly waking it up, fixing electrical bugs, and enjoying the [censored] out of it.

 

[Hethaerto]

Originally Posted By: Johnny
What we really need is a picture of that beauty.


http://m72.photobucket.com/albums/hethaerto/Porsche%20928/?src=www?pbauth=1_uLEBonVPfaLdh1h3YMYz2fjpWxo5ZpUfkpZddDsOu%2ByGUMJortr84mt6Tuuhq%2Bba9c0DQNGzkaV4%2Ftuk0iq3CemJyJB7EqS%2BT%2FW8m0zSsWXJ4v1j96O%2F%2BS82X8unbSAAU5WTwwl%2FY%2FNC7QETwYb3iOll0gwn%2BXVZR8GGIR76E%2Fc%3D

 

[Johnny]

That's pretty. Looks to be in great shape. How many miles are on it? Let's see if this link works better.


http://m72.photobucket.com/albums/hethaerto/Porsche 928

 

[cheetahdriver]

i agree with everyone on the HDEO. i believe that one of our resident experts has been using Delvac1 in this engine forever, with excellent results. johnny's recommendation of RotellaT6 is a excellent one as well. with the right oil, this engine is relatively bulletproof (for german).

paging Doug Hillary...

 

[Hethaerto]

The car just came alive with the XL 10w-30. I give it gas, and it revs quickly and speeds away.

 

[Johnny]

If you like Amsoil products, you should try this.

http://www.amsoil.com/storefront/afl.aspx

 

[sprintman]

What Audi Junkie said

 

[Audi Junkie]

I wonder if the "Z" in ZR-1 is for Zink?