I have an '88 928 S4 that I bought from a very meticulous owner that maintained it flawlessly. Not being terribly familiar with Porsche (I usually play around with old American dinosaurs) and wanting to keep the car as well as he had, I had to ask some basic questions. One of which was "What kind of oil should I use?"

He told me that Mobil 1 in a 15W40 was the way to go. I recall thinking that it was an odd viscosity, but I'm the noob here, so what do I know?

Well, the car is a quart low, so I went to purchase some. It appears that they don't actually make Mobil 1 in a 15W40. Was it discontinued? Was this simply a typo?
Should I use a different brand or a different viscosity?

I live in NY and the car is garaged, so it's rare that it will see extreme cold.
I drive the car sparingly and it's a 5 speed, if that matters.

 

I have done alot of reseach here on Rennlist too, and there had been many, many threads and debates. Most people/experts prefer 15w50 with high zinc content for those engines. Mobil 1 is very popular and so are Amsoil and Royal Purple.

There will be others chiming in.

 

High zinc 15 or 20w50 is the only way to go as an all around street oil. Choose your favorite manufacturer of it like Brad Penn, Amsoil, Royal Purple, etc.

Or you could check your owners manual for the correct viscosity for your temperature range.

Use synthetic if you like, just be sure that all of your seals are in exceedingly great shape as synthetic oil molecules are more uniform and smaller so it will leak more if you already have some oil weeping.

 

As a big-time n00b, 20w50 with high zddp was stressed to me by the PO.

He also told me that oil conversations fall into the same vein as politics & religion

 

He was probably using Mobil Delvac diesel truck oil, It is a good oil and has a high ZDDP content.

I have used it before and recommend it or Shell Rotella if your not going to run synthetic oil.

It is on sale at O"Reilly auto for $12.99 a gallon until June 23.

"Mobil Delvac 1300 Super 15W-40 is an extra-high performance, diesel engine oil that helps extend engine life in the most severe on- and off-highway applications while delivering outstanding performance. It meets or exceeds the requirements of the API CJ-4, CI-4 PLUS and CH-4 service categories as well as key original equipment manufacturer requirements.

Specifically recommended for the latest low-emissions, high-performance diesel applications equipped with aftertreatment systems using Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC) technologies.
Recommended for high-performance diesel applications including turbo-charged designs featuring Exhaust Gas Recirculation (EGR) Technology and diesel applications using older, naturally aspirated conventional designs.
On-highway, heavy-duty trucking and off-highway including: construction, mining, quarrying, and agriculture.

On-highway applications operating in both high speed/high load and short haul pick-up/delivery.
Off-highway applications operating in severe low-speed/heavy-load conditions using either low (500 ppm) or ultra low (15 ppm) sulfur fuels.
Recommended for use in high-performance gasoline engines and mixed fleet operations.

Diesel-powered equipment from American and European original equipment manufacturers.
Features and Potential Benefits:
Greater engine efficiency, long engine life and long oil life
Reduced low-temperature sludge build-up and high-temperature deposits
Lower oil costs due to less make-up oil during operation

Improved corrosion protection and extended drain intervals for both new and old engines using either low (500ppm) or ultra-low (15ppm) sulfur diesel fuel
Maintains viscosity in severe, high-temperature service for outstanding wear protection and long engine life
Faster oil flow and reduced wear during engine start-up in low

Brand Information
A premium, heavy duty, extra-high performance, diesel engine oil that helps extend engine life in the most severe on- and off-highway applications while delivering outstanding performance. Meets or exceed the requirements of the API CJ-4, CI-4 PLUS and CH-4 service categories as well as key original equipment manufacturer requirements.

Manufacturer Information
Nothing works harder to keep your car, truck, van or SUV running smoothly than Mobil-branded oils. From premium conventional to advanced full synthetic, high-performance to high-mileage - there is a Mobil-branded motor oil to help you go the distance time and time again. Delivering exceptional performance for vehicles of all ages, Mobil 1 advanced full synthetic motor oil keeps engines running like new by combating sludge, reducing wear and controlling oil breakdown. In fact, Mobil 1 is the world's leading synthetic motor oil brand, recommended by more car builders than any other brand of motor oil, and used by more NASCAR® teams."

 

20w50, non synthetic.
You don't want to use a thin oil in these engines.

 

If you can't find the same oil it would probably be better to top it up with something different rather than run it low. Chuck in any #w40 until you get round to an oil change. I was in NY in winter and it was freezing. Not sure 20w would be ideal if you parked the car outside for a few hours and then started it up.

 

15W 50 or 20W 50 if you are in the warmer States.

 

Well, after consulting this forum, the owner's manual, God, and my magic 8-ball, I decided to go with the Mobil 1 15W-50.

I thank you all.

 

Good choice for most drivers. Walmart sells a 5qt jug for under $30, get two and have some left over after the oil change. My cars have been swimming in it or years with good results.

 

Good man. Person. Whatever, sound decision.
Except for the Mobil 1 part.
;-)

Mark? Mark K?

J/k....Tarnation, every community, every forum, oil threads...eesh.

Anyway, my motorcycle runs 15W-40 for the combined gearbox and engine lubrication.
Point being, that oil has to ahve the JASO certification for the wet clutches. In addition to weight, API cert bears on the issue.

Recommendations to run a diesel or commercial certified oil with different detergent (and other) characteristics ought to be a concern that is explained by those advocating such, and that excessively high ZDDP can compromise catalyitic converters (if applicable). Note that I said excessively

Come to think of it, my synth marine oil would probably be a good fill given the high-load application and suitable viscosity (not).

Here are some datapoints- and some viewpoints, being a product pitch piece. I'm not advocating for the product and am not affiliated, it is just some additional context
http://www.drivenracingoil.com/news/...-in-motor-oil/

 

Racing has its own separate issues, way different from what a street car needs. As much as we all consider ourselves closet F1 champions, the reality is that there isn't much street driving on street tires can throw at the engine that might require anything more than what was originally spec's for the engine by Porsche. Race engines ee more sever service and have oil changed and analyzed after every race. Meanwhile, an annual change at 2-4k is a lot more common among owners here.

I've had great results from M1 over the years in many cars, but perhaps the biggest reason I use it is because it's inexpensive, readily available, and does all I ask of it. I have a tougher time finding conventional anythingW-50 around here. Plus the 5qt jug is handy for disposing some of the used oil after each change.