1989 Porsche 928 S4: what oil at 100K?

What grade of oil would one use in a 1989 Porsche 928 S4, automatic transmission, 100K? I say Mobil-1 "extended performance" synthetic
15W-50 is the best bet, though the opinions vary on this widely. The "extended performance" synthetic that Mobil-1 has is (at the moment) hard to find; does anyone know where it can be found online?
Is 10W-40 too thin for the 928? Reading misc websites I've seen people recommend from 5W-30 to 20W-50, so I'm understandably a bit lost on the issue of grade. But at 100K, I personally lean towards the thicker oils.
I will be (likely) purchasing this exact car shortly. Is the Fram (PH6583) oil filter acceptable for use in this car? It supposedly is, though the other (foreign-manufactured) OFs seem to be much larger. This car requires 9 quarts of motor oil, am I right? The Fram PH6583 seems too small. K&N doesn't make an oil filter (that I'm aware of) that fits this car; what manufacturer/model would be best so far as oil filters are concerned?
Also: Is synthetic ATF a good option for use in a car of this age/miles? Mobil-1 sells one, though I don't hear nearly as much talk about synthetic ATF as synthetic motor oils. Are they of any conceivable advantage?
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The "Extended Performance" 15w50 is just the new version of Mobil1. It is rolling out slowly. I work in an auto parts retail and it took a few weeks after we ran out of the old stuff to get the new stuff in. It is in now, however.

I have had an '84 928 with 200k + miles and use the 15w50, I have very little oil usage, and go about 5000 to 6000 miles between oil changes. I recommend you get the Mann filter or a Mahle if you can find it. I have personally had a Napa Gold filter blow off of my 914 when I had it, due to poorly cut threads on the (supposedly) top of the line Napa filter. I have seen fram filters "popped" out with the seam split around the base (total engine oil loss)
I figure the three bucks extra I spend above the cost of the fram means very little compared to the cost of the oil I run. Not to mention the engine.

Synthetic oils (and trans fluid) will not break down due to heat like standard, so they are a better bet, just don't start playing areound with non specified *types* of fluids and you should be fine.
Bernard

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Go here! Many thanks to Doug Hillary for this article. I believe it explains every thing you might need to know on lubricants for the 928. It is to be found at the below "Land Shark Oz site. http://www.landsharkoz.com/tt/ttlubricant.htm
Mark
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You may want to take a look here regarding Oil Filters.. http://minimopar.knizefamily.net/oilfilters.html I would either use OEM or a Pureolater Pure One (if you can find it).
GP

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F. Baker wrote:

What grade does the owners manual recommend for the climate that you drive the car in? Whatever that grade is, I'd use it.

The "extended performance" is just a re-labelling of good ol' Mobil 1. If its not available yet, do your next change with the correct grade of Mobil 1.

First off, most engines aren't super picky about grade, so they'll live happily on a pretty wide range of grades. The optimum balance of engine protection without being so thick as to waste power is what really determines the "best" grade. Thicker oil doesn't necessarily translate to "better protection" if the engine maintains enough oil pressure on thinner oil. In fact, thinner oils tend to get pumped more evenly throughout the engine, and circulate faster through the engine and thus provide a bit better cooling for the oil-cooled components (like the undersides of the pistons).
Secondly, 100k is NOT a lot of miles for a liquid-cooled v8. If its still got good compression, good balance of compression, low or no oil consumption, and good oil pressure, use the grade that is recommended by the manufacturer. I've got 4 different engines (1 Chrysler v6, three older Chrysler v8s), 3 with over 200,000 miles on the clock and 1 with 160,000, and I run Mobil-1 10w30 in all, which happens to be the recommended grade for them all. They all maintain good oil pressure at hot idle, and that's the point where oil pressure will fall too low if an engine's clearances have opened up too wide for the recommended grade.

I wouldn't run a Fram on a sewage pump, myself. Wix and Purolator make some of the better filters on the market. The Mobil 1 branded filter is also very good, although I think its a bit overpriced and I don't know if its available for that car.

Not much. ATF is far more stable and lives in a far more forgiving environment (no combustion by-products continually injected into it) than engine oil. IIRC, the 928 automatic uses good old Dexron-III just like Chrysler and GM did in the 80s. If you want a little extra insurance at more than twice the price, use Mobil-1 synthetic ATF. Otherwise, use a name-brand and follow the service schedule.
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Steve wrote:

1.
of
It's more than just a relabelled product. Whether or not it's a good idea for most car owners these days is debatable. They seem to have picked a market niche for the "regular" Mobil 1 and the "Extended Performance". The regular version comes in the 5W-30/ 10W-30 weights that most manufacturers recommend these days, and 0W-40 which is supposedly for many European cars. There's also the 0W-30 which I believe GM recommends for cold climates. I saw the first three at a local Wal-Mart.
The "Extended Performance" version also seems to come in the 10W-40 and 15W-50 weights that a lot of DIY owners like to use. I saw the new "EP" Mobil 1, and the kicker is that none of them carry the API "Starburst" or "Energy Conserving" labels. They also only come with the API SL standard while the regular Mobil 1 now has the newer API SM.

live
engine
translate
thus
True. There are so many people who were convinced that 20W-50 had to protect better because it was thicker. The likely thing that might happen is a small power loss due to internal drag, and worse fuel economy.

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The Mobil 1 filter is made by a contractor called Champion Labs. They make filters sold under any number of brand names. Some of them are OEM, house labels, etc. Many of their products are very good.

just
It would have been Dexron-II back then. I wouldn't recommend following some of the extremely high service intervals these days (i.e. never change the transmission fluid).
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y_p_w wrote:

I should have said a "replacement" product. Mobil-1 has now been replaced by Mobil-1 "Extended Performance" and (maybe) reformulated a little bit. If you look at the other oils (Mobil Clean 5000 and Mobil Clean 7500), They are replacements for Mobil's line of non-synthetic (MC 5000) and synthetic blend (MC 7500) oils. Mobil-1 extended performance is the only "real Mobil-1" fully synthetic oil.
See: http://www.mobiloil.com/USA-English/MotorOil/Home/Homepage.aspx
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Steve wrote:

you
grade
(MC
performance
They still have the original "Mobil 1" lineup. I didn't give the full set of what they now offer. It's, 0W-30, 0W-40, 5W-20 (for Ford/Honda/Mazda), 5W-30, and 10W-30. The 0W-40 is what Porsche would recommend, and it's close to the European Mobil 1 5W-40 from the factory. The 0W-40 is also supposed to meet the Mercedes Benz 229.5 standard for extended-drain oils, and it's not part of the Mobil 1 "Extended Performance" line.
I'm still not sure what's completely up with Mobil 1 Extended Performance. By going to the earlier API standard (SL) they can't use an "Energy Conserving" label - it's likely some sort of burecratic thing. I'm not terribly convinced that using one of these "extended drain" oils is better than regular Mobil 1 changed more often. Boosted additives often means less lubricating oil.
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y_p_w wrote:

They might *now*, but when the 928S4 was built, there was no such oil.

The API is notorious for occasionally *limiting* the amount of various additives that are "acceptable" for a given standard (SJ, SL, etc.) usually under the guise of wanting to limit chemicals that might poison catalytic convertors. Sometimes this has a very negative effect on the lubricating qualities of the oil- some of the limited additives are excellent extreme-pressure wear inhibitors (zinc) and others are excellent pH stabilizers that keep the TBN low during long drain intervals (one of these changes led to Mobil coming out with the "tri-synthetic" Mobil 1 a few years ago, which turned out to be pretty crappy oil compared to the previous and subsequent versions when API backed off on the requirement for their next standard). I haven't researched this particular case, but it may be one of those instances where Mobil feels that they can produce a better long-life oil with better long-term TBN under the SL standard than they can under the current standards. Given that the Mobil site flat-out states that "extended performance" contains "50% more SuperSyn,36 percent more anti-wear additives, and 37 percent more cleaning agents than the current Mobil 1," I would guess that it simply contains too much of one or more components to qualify for the newer rating.
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On Wed, 16 Mar 2005, Steve wrote:

TBN?
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Daniel J. Stern wrote:

Total base number- a measure of how well the oil is resisting acid formation during extended use, and one of the most critical parameters to look at when you are using oil analyses to tell you when to change the oil instead of just using the calendar or odometer.
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Steve wrote:

Of course I'm referring to Porsche's current list. When Porsche first started recommending Mobil 1, there were bulletins saying that they approved of all weights of Mobil 1 depending on ambient conditions or usage. It was probably not a great idea.
<http://www.alldata.com/tsb/Porsche/1089356400000_1093417200000_12-04/index.html0 <http://www.alldata.com/tsb/Porsche/1089442800000_1093417200000_13-04/index.html
Of all these oils, only Mobil 1 0W-40 is the one I've seen on store shelves. A shop I've used does stock Kendall Synthetic 5W-40 though.

I thought ZDDP was considered and antiwear additive, and that "extreme pressure" usually referred to the (mostly sulfer compound) additives used in gear oil. IIRC, these EP additives aren't well suited in motor oil because they wouldn't survive the higher temps.

That's what I was guessing too. However - they seem to be targeting this series at the car well beyond its warranty period. The car well beyond its warranty period is probably not going to have a factory recommendation beyond API SL anyways. Not that this matters with Porsche, which comes up with a list of approved oils, and of which (regular) Mobil 1 0W-40 is on the list.
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y_p_w wrote:

<http://www.alldata.com/tsb/Porsche/1089356400000_1093417200000_12-04/index.html0
<http://www.alldata.com/tsb/Porsche/1089442800000_1093417200000_13-04/index.html
I looked, and I notice that they don't recommend any xW-30 or xW-20 oils... then I noticed the earlier page that referred to the Boxster engine ;-)
Air-coolers have different needs.... :-)

You're probably right on the extreme pressure terminology. I was specifically referring to sacrifical additives (of which ZDP is one) that are effective under high-pressure, direct metal-to-metal contact that exceeds the film strength of the base lubricant. I was using "extreme pressure" in the generic, not the specific.

Which is FINE with me- all the cars I care about keeping forever are WELL beyond their warranty period! New cars are boring :-p
This has come up on another thread on rec.autos.tech as well, and resulted in a link to some comments made by a GM engineer at:
http://cadillacforums.com/forums/showthread.php?t2413&page=1&pp
If you plow through all the commentary and facts and replies (by the way, he believes any API-rated oil is just fine in the Northstar), you'll come to one point where he says that he wouldn't hesitate to run a Northstar right up to the built-in oil-life monitor's 12,500 mile limit, but would never do the same with an HT4100 because it has flat tappets, a gear-driven distributor, gear-type oil pump, and a non-roller timing chain, all of which eat up the ZDP additives in an oil much faster than all the other engine parts common to both engine designs (bearings, cylinder-to-piston friction, etc).
SO- if you ARE interested in taking the best possible care of an older engine that does have any of these features (mine all only share the flat tappets and distributor drive gear, because Chrysler v8s have always used gerotor oil pumps and I've got roller timing chains on them all), then an oil with a higher dose of ZDP is probably a very good thing to use, even if you don't run it to extremely high milage.
So i'll probably start using Mobil 1 Extended Life, but I'll still change it at around 7000 to 9000 miles, just like I've done for the last 15 years or so.
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Steve wrote:

run
non-roller
I've gone through that thread and he seems to be quite knowledgeable. However - I seem to recall that GM has recommended 0W-30 synthetic oil for those who run their cars in extremely cold climates. I read through the owner's manual for my dad's '96 Buick Regal, and even that recommends a synthetic 5W-30 below a certain temp (although the definition of "synthetic oil" was clearer then than now). That car came with rather specific recommendations that on 10W-30 be used if above freezing, while 5W-30 should only be used if less than 50 deg F.

older
them
I thought the big thing with ZDDP is that it fouls catalytic converters. There was some controversy that in the switch from the API SH to SJ standard, the result may have been an overall lowering of antiwear properties. The concern wasn't that the minimum antiwear standard went down from SH to SJ. Oil formulas included quantities of ZDDP that exceeded antiwear requirements, but supposedly the mandate to reduce zinc and phosphorous lowered the amount of ZDDP that could be used.

last
I didn't look closely on the shelf at Wally World, but it didn't seem that they charged a premium for it over regular Mobil 1.
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y_p_w wrote:

IIRC, it was exactly the same price at Schlep Boyz.
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Steve wrote:

seem
I looked again. Granted each Wal-Mart sets it prices differently, but the one I went to had "regular" Mobil 1 at $4.32/quart and $18.92 for a 5 quart jug. The "Extended Performance" was $5.40/quart and $24 for a 5 quart jug.
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