JasonAndreas

For the longest time in the USA, the 5w40 weight that PAG originally used in the 993 was not available in the USA, and so independent shops over here used 15w50 and the like.

RockstarBruski

Thanks everyone for your information and advice. I ended up having my local Porsche dealership use Mobile1 15w50 full synthetic and it is working nicely. Also, the dealership loaned me a 2020 Taycan 4s so that was fun to drive to cars and coffee on a Saturday while my 993 wasn't available for the day.

TDW993

[QUOTE=serval;17598296]Why?[/

This is why:

An oil with say 15w/50 will have a different centistoke value (unit of kinematic viscosity) than another brand or even the same brand but different use with the same advertised viscosity. I alway look at the typical climate I am in, the sort of driving I do and the ZDDP amount. Where I live, Australia, it is very hot in summer and quite mild winters. The best oil that meets all my criteria is Brad Penn 20w/50. It has a nice cSt value when cold (taken at 15 deg C from memory) and a nice numbers when hot (100 deg C ) which is where the measurement is taken.
You really need to look into the data sheet of any oil to make an informed decision that suits and compare the data with other oils of similar viscosity to get an accurate benchmark. The viscosity on the bottle is only a rough guide for the average Joe that doesn’t really know or care about the oil he puts in his truck.

pdxmotorhead

Wrong forum.. oops. ignore this one.

fsa

To: bmoody33 in post #32
What does "working nicely" mean?

M. Schneider

At the risk of kicking a dead 993 horse .... Mobil 1 10W-40 (edit) and M1 15W-50 ... 1st OC @900mi fast forward to today @ 80K something miles.
The coupe has largely seen use in late spring, summer to early fall. Be it in N. ATL or Vail. .A fresh M1 10W-40 is the winter storage fill. .The Hot-Lanta summer or the hot summer Colorado mountain days, it's a summer M1 15W-50 fill. . All OC is DIY.

Bill Verburg

Assuming that the M1 15w-40 is from their Delvac line of truck diesel oils the ZDDP concentration appears to be 10,000ppm to 25,000ppm that;'s mighty high

Gbos1

M. Schneider

Ooops, edit; Sure 10W-40 Mobil 1 of the day 1997, 1998. Hey, memory is slipping.

MarinS4

Things I know about oil….
The wider the weight spread (10-40 etc) the more additives it takes to accomplish that. Those same additives break down oil sooner.
You can’t look at ZDDP without looking at the detergent package. More detergent offsets the benefits of ZDDP. So some of this diesel oil with high ZDDP counts may not be as advantageous as it appears.
Synthetic oil flows better cold than dino oil. This is when the most wear occurs during startup.

Opinions….
Motul 300v is spectacular oil, it was spec’d by our BMW race engine builder.
I really like the Mobil 1 20-50 V-Twin oil for our cars.

TDW993

Again, not entirely true WRT viscosity. A synthetic 40 grade will always be a 40 grade and a 50 grade will always be a 50 grade. That’s is where they start off at as the base oil is the higher grade that is to achieved. You are correct in saying that there are additives to achieve the W rating though. A non synthetic requires additives and fortifiers to achieve the desired W ratings and hot viscosity. That is why synthetic are better between extended oil changes as they remain consistent with the viscosity as their base viscosity. Non synthetic oil will lose its viscosity over time. In saying that, I use Brad Penn mineral oil which I feel suits my needs best as I want the high zinc levels and I do regular oil changes.

This is a really informative read re: oil and viscosity. It is very in depth but clears up a lot of misconceptions that get rehashed over and over and over.

https://www.ferrarichat.com/forum/th...e-this.136052/

Cheers
Todd

M. Schneider

TDW993 -
Many thanks. The link is a valuable read ala OIL.

Bruce Anderson (RIP) of 911 fame- (former Technical Editor at Porsche Excellence magazine, author of 911 reference books, in addition to the Founder-Principal of his long-standing Mountainview, CA shop) used to say "When cold starting a 911 (air-cooled) drive as if there's an egg between your foot and the accelerator pedal and never exceed 3K RPM until operating temp occurs".

A time-honored cold start practice from a 911 air-cooled master.

abiazis

Ran Mobil One Synthetic 15-50 for 17 years, ran 0-40 Mobil One for one oil change - too much usage, back to 15-50 Mobil One for 4 years, and the last year used Motul Synthetic 10-60.......car uses less oil with the 10-60 versus the 15-50.......was using a quart every 800 -1000 miles....now up to 2,000, 1/4 quart usage........

Bill Verburg

The only issue wrt to oil for our cars stems from the desire of the US government for a 10yr emission warranty on new cars, this lead to the reduction of ZDDP in some oils, specifically the lighter weight oils that the manufactures adopted for their new cars, an additional impetus for the lighter weight oils was the government's CAFE specs, There is little to no debate that the oil engineers skimped on additive packages which have always been adequate and if anything have improved over the years

The newly required low ZDDP oils were quietly introduced to little fanfare w/ the API classified SJ oils in 1996, note that the only oils that were mandated to have reduced ZDDP were the 0w-20 thru 10w-30 oils, The oil manufacturers were free to formulaate their oils as they pleased, some stayed the course, others reduced ZDDP by varying amounts. It wasn't until years later when engine builders started noticing unusual wear that the issue became more noticed by the general public. Anecdotally an MD friend who switched his new 964 to an oil w/ low ZDDP(though still a 0w-50 weight) required an engine rebuild after only a few years of use

M1 15w-50 was reduced a bit, it went from the SH standard 1095ppm P and 1427ppm Zn to SJ 1058ppm P and 1348ppm Zn, these #s come from period oil analysis, the M1 product spec sheet of the era says 1200/1300 which continues to be the stated value to this day



period oil analysis of the M1 20w-50 V-twin was 1084/1377 current factory claims are 1600/1750 which has also remained the same since the '90s, this is getting to the high end of the comfort zone except for brake in oils where it is on the low end

For years Porsche advocated the use of M1 0w/40 in our cars it's specs are 1000/1100 same as when it was introduced, this is at the low end of a comfort zone for ZDDP levels, When Porsche introduced their own branded oils the stopped pushing the 0w-40 , I wouldn't be really comfortable w/ either their old or new recommendations mostly because they refuse to publish ZDDP specs, current oil analysis of the current Porsche 10w-60 shows 940/1007 again a bit on the low side, possibly below the comfort zone

Magdaddy

Why has no one asked yet, if not having the engine undertray installed negatively effects oil viscosity or usage?

There was a time on this forum when that would have been asked on page 1.

We are slipping my friends…slipping I tell ya!