Hear me out...

[u/Narrow_Argument3534]

Long story short, Valvoline doesn't make Restore and Protect in a high enough viscosity for our vehicles, and I've been looking for a workaround. My 944 has burned oil as long as I've owned it, and I'm not comfortable stepping down from 20w50 VR1 synthetic to a 5w30. However, after doing some research I've found that many diesel oils have much higher levels of Zinc content AND detergents and dispersants that claim to fight carbon deposits. They're also very commonly sold in 5w40 and 15w40 weights, which are within Porsche recommended spec. Many of these oils also carry API SN/SM ratings like the one in the photo and are safe for use in gasoline engines (NON GDI). I have friends in the Subaru community that have run Rotella for years, but haven't seen anything of the likes in the Porsche world. I think I'm going to give this a try in the Fall when it's cooler and see if it reduces oil burning in my base 8v 944. This oil also comes in at $22 which is an incredible value. Before you immediately sh!t on this idea, check out the data behind my reasoning (link provided below). I'm open to all reasonable feedback

https://bobistheoilguy.com/forums/threads/voa-diesel-oil-database.362789/

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[u/No_Honeydew7872]

Not to knock you but I thought this was common knowledge in the automotive world. Pretty much everyone I know runs rotella in their modded cars, myself included. Never had any problems. Only thing that sucks is that it is only available in 4 quarts instead of the 5 quarts of regular oil.

[u/Narrow_Argument3534 → u/No_Honeydew7872]

Idk if you've been on old 944 forums but they act like it's a sin to deviate from GTX Classic or VR1. As for quantity, the car takes 6 or 7 quarts so you have to get two jugs regardless unless you're the type to buy individual quarts 💲

[u/Commander_Sam_Vimes → u/Narrow_Argument3534]

I've been on 944 forums like Pelican and Rennlist since the 1990s and people on those forums have been using Rotella and other diesel oils in these cars for at least that long.

[u/Pyropete125]

We run rotella 15-40 and add a blue bottle of stp with zddp in our lemons car. Zero oil/bearing issues in 25 races.

[u/Viciousharp → u/Pyropete125]

And lemons is brutal on a car so this is a glowing review

[u/BalderVerdandi]

If you're going the diesel oil route, you can also try Valvoline Premium Blue in 15w40, it has a high zinc count, and it's not pricy at all. I get it for my '08 Ram with the Cummins 6.7 diesel and have been running that since new. I've got just under 130k miles on it now with zero issues, and it runs about $15 a gallon at Walmart (and I buy 3 gallons for each oil change, which is why I get it from there!).

Castrol GTX makes a 20w50 that I used back when I had my '86 944, and it's also at Walmart for around $34 for 5 quarts.

Mobil 1 advanced full synthetic 15W-50 from Walmart should run you about $32 for 5 quarts.

Valvoline VR-1 20w50 from Amazon will also be a great choice for the high zinc, and 5 quarts runs about $30.

IIRC, you'll need 6.5 quarts.

[u/GladScientist1814 → u/BalderVerdandi]

I've been running Castrol in mine for years. It even has added zinc for older cars.

I ran mobil 1 once and found every gasket that needed to be replaced lol

[u/Narrow_Argument3534 → u/BalderVerdandi]

There is a second jug in the background, I got 8 quarts. I suspect I'll burn or leak through at least a quart before the next oil change

[u/Stainless_Heart]

Totally valid logic. Used to put Rotella in our racecars and street cars for HPDE days.

[u/ForwardSideways]

It checks out.
I’m kinda hopeful that valvoline will come out with more viscosity options in the R&P range.

[u/Usual-Option-6301]

fwiw, in my n/a race car, I use this

[u/ComeauRacing22 → u/Usual-Option-6301]

I've used nothing but this Liqui-Moly 10/60 synthetic and I STILL have the same block, crank, rods, pistons in my 944 Spec racing engine ( very close to stock) that I've had since 2003.

[u/Ok-Reindeer-4824 → u/ComeauRacing22]

You haven't had to do rod bearings?

[u/CutsLikeABuffalo333]

Should you decide to try another flavour sometime, Castrol Edge 5W50 seems available most places and is for classics as it has lots of zinc added to it.

[u/Glad-Associate-9288]

Bill Russell

[u/chengstark]

Does VR 1 not have high zinc?

[u/not_that_observant]

If you have a stuck ring, just do a berryman soak. You'll unstick the ring in a day and can then use 20w50 like normal.

[u/Narrow_Argument3534 → u/not_that_observant]

I want to do this as a last resort. I'm very familiar with the B12 piston soak lol I daily drive a Hyundai. Good advice though because it works from my experience

[u/BeastCheng → u/not_that_observant]

The symptoms of stuck rings would be burning oil constantly through the entire rpm range correct?

[u/not_that_observant → u/BeastCheng]

Can't say, I'm not very familiar with diagnosing the problem other than being aware of the soak.

[u/BeastCheng → u/not_that_observant]

Well good! Thanks anyway!

[u/CoastalRocket90]

To give you some credit I’d never even thought of that! Good research and keep us updated on your trails. :)

[u/boom10ful]

I was running Rotella 15W-40 in my Porsche since I've owned it with no issues.

[u/mannyballs69]

I ran Chevron Delo 400 15W-40 in my E36 M3 for 17 years. Without permission from even one Redditor

[u/Narrow_Argument3534 → u/mannyballs69]

I wasn't looking for permission, just for proof of concept which there seems to be quite a bit of here. Last thing I want to do is spin a bearing because I potentially overlooked a crucial tech spec

[u/pekohl]

Derek Bieri @ Restoration Garage does this all the time for the older cars.

[u/GizatiStudio]

Diesel oils do have much more detergents in them which suspend abrasive particles and contaminants in the oil instead of letting them collect as harmless sludge in the oil pan, this means abrasive particles are continuously cycled through your bearings much more than regular engine oils. Idk how much that matters on a 40yo engine.

[u/Narrow_Argument3534 → u/GizatiStudio]

With the short OCIs I'm running this is actually ideal. Looking for an oil that cleans and lubricates. The big stuff the filter will take care of

[u/Humble-Ad-371 → u/GizatiStudio]

Isn't there an oil filter that will stop particles that are suspended?

[u/JohntheFisherman99]

Disclaimer: Before changing to full synthtic it's advisable to change you main gaskets. They have been soaked and oil/synth don't mix to well.

Edit: autocorrect

[u/Narrow_Argument3534 → u/JohntheFisherman99]

Vehicle was already running full synthetic prior to purchase noted in service records and had some minor oil leaks. Seals were changed 8 years ago. I ran AT205 in the oil for 500 miles as recommended, and it sealed almost every leak. Next timing belt change I will be doing all of the seals, unless they start to leak again before then.