Jim Chambers

Dealer from whom I purchased my '90gt installed Castrol Syntec 5w-40.
I don't have an owners manual to see what Porsche called for back in 1990.

I am a long-time user of Valvoline 20-50 dino oil in all my older Porsches, including several 928's. Except for my '04 Boxster and a '95 993 I once owned, I have avoided synthetics, which I assume Syntec is.

Thinking of changing to the Valvoline, or possibly Brad Penn 20-50 which I use in my 914. Opinions?

andy-gts

Many oil opinions. search is your friend. I do have a print out on oil from greg brown(well know awesome engine builder) .He likes torco and another brand. I will see if I can post tomorrow as I am at work.
andy

the flyin' scotsman

IMHO I use the most recent oil technology so Mobil 1 15w50 is in the car.

The engine has had all external gaskets replaced and now uses no oil at all and runs perfect.

IcemanG17

the #1 thing to consider is how you drive your 928.....if you cruise easy on the street...then anything will work just fine....if you plan on doing trackdays with lots of time in the upper RPM's then you will need something better...... like Amsoil or redline

Mongo

woah where do you get 5W-50? I have not seen that at any local stores here.

hacker-pschorr

Not available in the US and IMO way to wide of a "spread" for my cars.

5w-50 is 5 weight with added modifiers to protect like / act like (pick an argument) a 50 weight at 100 degrees Celsius. As it breaks down (all oils do) the modifiers also break down lowering the "hot" viscosity.
The wider the spread, the more modifiers needed.
The more modifiers the faster it will break down....in theory

Some claim new oils do not "suffer" from this
Others claim if you change your oil every 3k it's not an issue.

I don't care, 15w-50 in my 928's.

FWIW as for the "newest" technology..... has given Mobil 1 a way to sell a "synthetic" oil that is not 100% synthetic.

I'll be switching my street cars to Brad Penn next year (except for the Ferrari and SAAB - Redline for those). As for the track car, not 100% sure yet. First I have to remember where I parked it.

I tried 5w-40 in my supercharged 81 for about three days in July a couple of years ago. My stereo was unable to drown out the lifter noise so I dumped it out and went back to 20w-50 RP (it's all I had at the time...)

jcorenman

Jim, either of your "comfort" oils-- the Valvoline or Brad Penn 20w-50 -- would be much better than what is in there. Unless you live in Finland and are planning a crossing of the polar cap, 5w-anything is too thin. I'm with Eric on that.

The other issue is ZDDP levels (zinc/phosphorus something-or-other), a high-pressure additive which protects the cams and lifters. Brad Penn has plenty (>1000 mg/L), as does Mobil-1 15w-50 and Amsoil ARO 20w-50, not sure about Valvoline but I suspect it is OK also. Most modern/lighter oils don't have enough.

Jim M.

I believe all Porsche models came with synthetic from 87 onward. So synthetic is what Porsche recommends. The weight is dependent on the temperture range of the driving.

Glenn Evans

An image of the page from the MY90 Driver's Manual dealing with engine oils is at http://928.landsharkoz.com/Gallery/t...lt.aspx?Page=2

Whatever viscosity grade on the chart you select to suit your climate, you must select an oil with an adequate level of the anti-wear additive zinc dialkyldithiophosphate (ZDDP). The belief that phosphates destroy catalytic converters has driven ZDDP contents in many oils down to level which are ineffective at preventing wear in flat tappet engines like the 928's and "advanced" substitutes have not prevented excessive wear. This issue has raged on the 993 and Boxster Rennlist forums (see "The latest on Mobil 1", or similarly titled thread, on the 993 forum.) The detrimental effect of phosphorus on cats probably is real to the el cheapo cats fitted to many new cars these days, but a local mechanic here in Sydney maintains that Porsche cats are of high quality and exhaust gas analysis shows that many early Porsche ones (MY86) still are effective.

Check the online Technical (aka Product) Data Sheet for any oil you are considering using. You should look for an oil with zinc and phosphorus levels of at least 0.10 per cent each (1000 ppm); preferably 0.12 per cent (1200 ppm). Personally, I will not use an oil in my car for which the zinc and phosphorus levels are not publicly available and adequate. Oil companies seem more compelled to disclose oil specs in the US than they are in Australia.

Avoid oils with the API "Energy Conserving" Donut and/or the ILSAC CJ-4 rating (found on oils with an API SM rating and xxW-30 viscosity grade or less), as these must have a phosphorus content of 0.08 per cent or less, meaning that the ZDDP content will be too low to be effective in our engines. The European ACEA specifications have more stringent wear requirements than the API specs, and the A3 rating has the most stringent high temperature high shear and stay-in-grade viscosity requirements.

Note that some well-respected US oil companies, like Brad Penn, don't submit their oils for API or ACEA testing. This may be so that they are free to use higher ZDDP levels, but I am guessing.

You may find http://www.lnengineering.com/oil.html interesting.

odurandina

i have always liked the idea of middle-of-the-road viscosity oil with zinc for Porsche V8 engines + the laws of physics... what i am saying is there is some leeway... where with other Porsche engines, even Subaru boxer engines - there is less.

mark kibort

amsoil. hard to argue with 110 race days on a single motor and no signs of wear, or the other 4 engines we have been beating on . one stroker and 2 stock builds. (or redline, or other oils that dont turn to water when they are cooked! )

928 at last

Read a lot here and now know far far more than I ever wanted to about motor oils.........
I've been running the Brad Penn 20-50. "The Green Oil"
Mainly because it's got the ZDDP jacked.
So far...so good , no Issues.

turbochad

Brad Penn 20-50 summer, 10-40 winter. If you have access to it this is the way to go. I get it here locally at a petroleum supply house for $3.45 per quart. It is a much better deal than straight synthetics for better oil. I have been very impressed with the performance of BP. The ZDDP levels are just right. No more oil concerns with BP.
Chad

GregBBRD

Brad Penn 20-50 is a good oil. That formula is supposed to be the original 20-50 Kendall "green oil". We ran Kendall for years...until they changed it. The only "down side" to the original Kendall was that all the engines we ran it in used slightly more oil than with other oils. I always thought that this way because the oil was very slippery and difficult for the rings to wipe it off the cylinders. However, I once saw a comparision of flash points of oils and the Kendall was lower than almost all others, which might mean that the engines simply burned more of it.

Tough to find a better oil than Torco TR-1 20-50, for what our engines need. It has all the "needed" additives and will improve the oil consumption issues that plague the GTS engines.

danglerb

Oil IMHO is 90% marketing baloney, but "better" oil is still cheap compared to everything else it takes to keep a 928 happy, so no good reason not to use a premium oil. Shell Rotella T works fine for me, and goes in all my cars.