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Tigger937

10W30 in a 924??? Has anyone tried this?

http://www.boss302.com/oil.htm

Comments?
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1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

Lizard · Posted: Sat Aug 27, 2005 12:45 pm Post subject:

Cannot really say anything about the range of viscosity being that bad, however his 3k between oil changes is off ESP for synthetic oil, so I wouldnt believe it all.
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3 928s,

dwak · Joined: 03 Nov 2002 Posts: 839 Location: Eastern Ontario

Although I'm a fan of synthetic oil, I and others have noticed problems with it and older Porches. As if it's better penetrating properties caused it to find new ways to exit the engine via seals, etc.

dwak

Lizard · Posted: Sun Aug 28, 2005 4:14 am Post subject:

correct dwak, it is a good idea to replace alot of the engine seals when you switch over, or deal with the leaks

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3 928s,

kaffine · Joined: 13 Jun 2003 Posts: 644 Location: Las Vegas

You can deffinatly tell he works at quick lube joints. The problem of doing oil and filter changes at 3000 miles when the manafacture recomends much longer service intervals.

Filters are the most effecient at removing dirt at the end of it's service life. As the filter gets plugged up by dirt it forces the oil to go through smaller and smaller passages which trap smaller paritcles. A new filter will allow much larger particals through it than one at the end of it's service life. This is why it is common for manafactures to recommend replacing the filter at every other oil change.

I do oil analysis to determine oil change intervals. I was running 10,000 mile intervals with dino oil with close to the same readings as 3,000 miles. If I went to 12,000 miles the wear started to increase but the fuel dilution was still very low even with mostly city driving most likely the oil filter had reached it's capacity. I haven't had enough oil changes with synthetics to determine change intervals yet but I have had one that went 15,000 it showed that the filter needed to be changed but the oil was still good. I now have a suction pump that I can use to get an oil sample without draining the oil. I'm thinking about putting restriction gauges on the filter so I can see what the pressure drop is across the filter to determine when to change it. I would really like to get an on board oil analysis system but I don't have that kind of money.
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80 924
80 931

The best desciption of an atom boils down to something unknown is doing we don't know what.
Sir Arthur Eddington

ozarknight · Joined: 27 Jul 2005 Posts: 27 Location: Rolla, MO

Previous owner of my 924S replaced the oil drain plug with a drain valve. While is intent was to make oil changes easier, it's also a great way to get oil samples for analysis.

Doug
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'88 924S Slate Gray Metallic

Tigger937 · Posted: Mon Aug 29, 2005 5:50 am Post subject:

Kaffine, how does the oil life compare between your 924 and 931? Also, can you provide more details as to what the analysis consists of?
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1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

kaffine · Joined: 13 Jun 2003 Posts: 644 Location: Las Vegas

I haven't had the Porsches running long enough to do oil analysis on them yet. I have used 2 diffrent labs to have the analysis done. Petroleum Products Monitoring and Blackstone Labs. PPM is a little cheaper but they don't provide help interpeting the results. I collect a sample of the oil in a plastic bottle and fill out the info on what brand and viscosity of oil was use mileage on oil and on engine makeup oil added ect. and what type of engine it is. They test for viscosity, fuel dilution, coolant, wear metals, additives, acididity of the oil, dirt.

On my brothers truck since it has a common engine Cummins 5.9L ISB they list averages for that engine from all of them that they have tested, average of my fleet and averges for that unit. It is recommend that you do the oil analysis regulaly so you can catch any trends on that engine more easliy.

I'm still learning how to use oil analysis I had started studing it when I first started but I have been to busy to keep up with it. One of my freinds worked at a truck shop one of their customers used oil analysis every time the oil was changed the customer kept very close tabs on the results. When the results got to a certiain point when the truck went in for the next oil change they would change the whole enigne instead because they knew it was about to fail. That was a very large fleet sevral thousand trucks

http://www.blackstone-labs.com/
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80 924
80 931

The best desciption of an atom boils down to something unknown is doing we don't know what.
Sir Arthur Eddington

Tigger937 · Posted: Sat Sep 10, 2005 6:53 pm Post subject:

I guess I was speaking more in terms of the viscosity range, rather than change intervals. Over the years, I've used a lot of 10W40, although not in the Porsches, and I can say every one of those vehicles started blowing smoke on startup after approximately 60-80K miles. Oil consumption would increase to approximately 1 quart every 1500 miles. My change intervals have consistently been around 3000 miles. In the Porsches, I've used mainly 20W50 and am suffering the same problem. I started using 10W30 in my 1st truck and the problem disappeared. Oil consumption remained below 1 quart every 3000 miles, even after 200,000 miles! I'm on my 2nd truck now using 10W30 and the problem has not re-appeared. The narrower viscosity oils such as 10W30 contain less additives like viscosity index improvers, etc. It's generally these additives that wear out, not the base stock oil, especially in the turbo cars with the added shear and heat.

So, as a test, I've switched to 10W30 Mobil 1 in the Porsche even though the owners manual did not recommend anything below 10W40. Another benefit I've noticed with the lighter weight oil in the trucks is improved gas mileage, on the order of 10% or so. Has anyone else tried this or experienced this problem?
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1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

Gram · Posted: Sat Sep 10, 2005 7:17 pm Post subject:

Interesting. My 924 handbook suggests 10W30 up to 20 degC. We get to 30C here so I should be using 10W40 or 50 according to Porsche. (Page 75)
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'82 924 NA Euro (hers)
'98 Audi A4 TDI (ours)

Tigger937 · Posted: Sat Sep 10, 2005 7:45 pm Post subject:

My 1981 924/924 Turbo (US Spec) Owner's Manual states on page 80 the following:

-snip-
For all year round filling (oil change intervals 7500 miles/12000 km) use multi-grade oils SAE 10W40, 15W40, 15W50 OR 20W50. The 20W50 oil should not be used at constant temperatures below +5°F/-15°C. The 10W40 oil should only be used at termperatures below +50°F/+10°C.

Porsche recommends the use of single-grade oils only if multi-grade oils are not readily available. The following viscosity can be used: In summer SAE 30, in winter SAE 20W (only at constant temperatures below +41°F/+5°C). Porsche does not recommend the use of oil additives.
-snip-

No mention is made for 10W30.
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1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

JamesWilson · Joined: 10 Jun 2005 Posts: 132 Location: San Diego, CA

I second the use of oil analysis, I use Blackstone Labs www.Blackstone-labs.com . Quick turnaround, good price, and excellent explanaition of report. I have used UOA (used oil analysis) on many many cars and it can easily point out engine wear and potential failures.

UOA consists of measuring certain levels of elements (Ca, Pb, Si, Ar, etc) that are usually present in a given sample of certain brand and weight of oil (all already categorized so that an elevated level may or may not be "normal", and is also categorized per engine type. Example-- many V8 GM engines have very high copper levels present in UOA, but that is "normal" for that engine, though could spell dangerous bearing or other material wear in say a Toyota engine that typically sees very low copper levels.) It also shows what ACTUAL viscosity the oil is at the time of sample, varying from its "virgin" state (available through VOA...virgin oil analysis, already on file for the most part).

Different oils perform differently in different engines. My old Mazda rotary required a 20w-50, but would quickly shear down to a very light 30-wt after even 2K miles of use. I found a very shear-stable oil that worked well for that engine, as well as one with more Moly and Ca as the rotary has stationary gears that needed more extreme pressure (EP) additives, as well as the ability to counter-act Fuel Dilution (also tested in standard reports), as well as showing possible signs of damage from water or coolant present , even as small as 1% (also std testing). What started with a Mobil Drive Clean 20w-50 should have been more than sufficient for the Mazda ended up not being up to snuff. A switch to Castrol Tection Extra 15w-50 diesel and finally Royal Purple 15w-40 diesel found the "perfect oil", if there is such a thing, for THAT PARTICULAR ENGINE. Best $20 I ever spent, and they keep your analysis on file and compare trends side-by-side to see what is wearing, or even if the air filter needs to be changed (elevated silicone levels).

Certain oils also are different weights within their viscosity range. In actuality, a Mobil 1 10w-30 (old formula, non-EP) is a "ligher" 30-wt than its 5w-30 counterpart. Mobil 1 0w-20 and RedLline 5w-20 both have similar viscosities to a light 30-wt rather than a true 20-wt. Castrol SLX 0w-30 ("German Castrol" in the US, pours out green or gold depending on the batch #) is actually a solid 30-wt that is "thicker" than most synthetic 10w-30's! You can usually find such number on tech sheets from oil manufacturers, or search online for each product's VOA.

I ran my first OCI (oil change interval) with Royal Purple 15w-40 diesel synthetic in my 931 and sent the sample off last week, waiting eagerly for the results. My current oil is Mobil 1 EP 15w-50, I will run it for an equal interval to see which oil ends up being better. I also plan on testing RedLine 10w-40 (you can typically go down a weight with RedLine, even with a turbo car hard on oil), LubroMoly 5w-40, Mobil Truck & SUV 5w-40, and Royal Purple Racing 51.

Ready to become an oil junky?? Visit www.BobIsTheOilGuy.com and be sure to slum around their oil forums, good mix of chemists, engineers, and ex-lab guys who use solid UOA and real-world testing to determine an oil's worth....in each engine.
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'82 924 Turbo (not stock) - soon returning home?
www.AffordableRacingData.com

Tigger937 · Posted: Thu Sep 22, 2005 3:27 am Post subject:

Thanks James. That was exactly the kind of info I was looking for. Keep us posted on your 931 UOA results.
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1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

Paul · Posted: Thu Sep 22, 2005 10:02 am Post subject:

Porsche's latest recommendation is that all Porsches ever made should use Mobil 1 0W-40.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The following thread and information by Doug Hillary is an excellent primer on oils for our Porsches.

http://forums.rennlist.com/rennforums/showthread.php?t=154690

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black