jcorenman

Greg, I think that is generally understood, that's why there's been so darn much discussion-- here and elsewhere. And like most things internet, there is a rich mixture of fact and "nonsense". It's an absolute mess.

What seems clear is that most of the ordinary off-the-shelf motor oils are no longer suitable for our engines. I doubt if we'll ever see any hard evidence, just things wearing out before they might have otherwise. Who can say that a worn cam at 150,000 miles might not have gone 250,000 with some different lubricant?

However "specialty" oils (e.g. heavy-duty, mixed-fleet, off-road or racing oils) are not limited by the API SM/GF-4/whatever specifications and can use traditional formulations with higher zinc and phosphous (ZDDP) levels. Whatever we think about the new standards, certainly we can all agree that the traditional additive packages have a very long and successful history with these engines. So why change them? There's been no suggestion at all that SM or GF-4 oils are somehow "better" for our engines.

Greg, are you sure that it is the "SM" classification, and not the "GF-4", that limits zinc and phosphous (ZDDP)? The reason I ask is that the May-2008 'Mobil-1 Product Guide which I mentioned above says that Mobil-1 20W-50 has 1200 ppm phosphous yet meets SM (but not GF-4). Confusing. But I have seen other references that say that SM is a problem also, not just GF-4.

My concern with just dumping in some ZDDP additive is that nothing in motor oil works alone, the balance of the various additives makes a difference also. Like John Muir saild, "It's all connected".

I just looked at the Mobil-1 20W-50 I've been using-- it is some "old stock" that I've had for a while, and marked "SL". It would be interesting to send off a virgin sample of that along with the newer "SM" marked version for testing.

Another interesting paper is this this tech-bulletin from Amsoil, which lists the phos/zinc levels of certain of the Amsoil oils, including two different 20W-50 oils (ARO "premium protection" and TRO racing oil- which I assume is what Mark K is using). ARO is a "SL" rated oil with a phoshporus level of 1265.

Cheers,

GregBBRD

Ernest: That's the stuff. Works great. Will not solve oil consumption issues (see below).

Tom: No, I don't. I started switching people over and using additives, from the very beginning. I was hoping to avoid seeing cam damage in "my" cars.

Here's another interesting bit that we found out, once we started switching over and not using additives. The GTS models tend to use lots of oil. Big stroker engines, on the street, seem to also use more oil....probably because the pistons are so stinking big. At any rate, we switched over Joe's GTS before he left for the "Sharks at the Lake" thing. He reported back that his oil consumption had essentially quit. I have a customer with a street stroker engine that used a quart every 600 miles or so. Switched him over to Torco and he is no not adding any oil.

Hmmm. Interesting. If I owned a big oil company...would I want to rely only on the profit from just people changing oil....or would I want to make sure that people had to add oil between changes? Hmmm....let me think....

ew928

Thanks for the info, Greg.
JCorenman may have something with the GF-4 rating.
Heard the Mobil 1 guru/father speak at PorschePlatz at Lime Rock.
Someone brought up the Zinc issue and he explained that most Mobile Uno are not low Zinc oils.
BUT, the low fuel consumption super light oils specced by Automobile Manufacturer to max fuel economy are low Zinc (think it was less than 0.8 percent, I think).
The Low Zinc M1's are 0w-20, 10w-30, 5w-30 (was it 5w--20) and another light oil.
Wish I had a camcorder to tape important information like that.

I've got the 88 S4 motor. Can't get it to burn oil unlike my GT and GTS younger brothers.
Followed 2 GT's on the NC to PA drive back from SITM. Everytime the GT's would hammer down to pass obnoxious traffic, I'd see a nice puff of smoke come out the tailpipe.

GregBBRD

Torco makes a special oil just for break-in that we've been using. Loaded to the gills with Zinc and Phosphorus, apparently.

Adam Geist

OK, I just checked the Amsoil website and they have a 20W-50 synthetic and a 15W-50 racing oil.

Which one should be used in the 32V engine?

928 at last

Hey Guys/Gals....
Greg's link works when you use the correct URL for LN Engineering..........
Try
http://www.lnengineering.com/oil.html
Good article.
Rob.

wds928

Very informative info.

Mark, which Amsoil have you been using, Racing 20w-50 or the regular 20w-50?

Greg, which Brad Penn do you put in 928 engines?

I've got 150,000 miles on my GTS and it uses oil and has since I bought the car 5 years ago at 103,000 miles.

Looking back at my Blackstone Labs reports, my last change in April 2008 showed Phsphorus at 1040ppm and Zinc at 1328 ppm, which is very close to my prior oil changes.

I've looked at the Mobil 1 specs and the silver cap 15w-50 and the Amsoil 20w-50 specs and the are very similar, however, Amsoil is a SL spec oil and Mobil 1 is a SM spec oil. Can't seem to find info on the specific zinc or phospohrus content of the SM Mobil 1, but since I only have a couple of quarts left, I may buy a couple of gallons of Amsoil or Brad Penn and change it out.....and send the Mobil 1 to Blackstone Labs for testing.

By the way, I've been using the same Mobil 1 in my 1992 Mercedes 500E (183,000 miles) and it consumes much less oil than the GTS engine. The Blackstone Labs reports have similar Phos and Zinc numbers to the 928.

I usually change the 928 oil once a year, as I only drive it about 6,000 to 7,000 miles per year. The Mercedes oil is changed twice a year, around 7,500 miles each time. Maybe I should get a 16 gallon drum of Amsoil!!!

jcorenman

OK, for anyone not thoroughly sick of this topic here's another interesting article that Google found, this one from "Street Rodder" magazine. (When the times get strange, folks tend to form strange alliances).

http://www.streetrodderweb.com/tech/...questions.html

This is actually page 2 of the article and is a series of questions posed to reps from Amsoil, Pure-Power (dino oil popular with the hot-rod crowd) and Torco. (Page 1 is interesting also, click the "Prev" link at the bottom).

A couple of things struck me. One is that Torco's additive package includes "liquid molybdenum" (as well as zinc and phosphorus), for decreased wear. Could the moly explain Greg's obsevation that Torco reduces oil consumption in GTS and stroker motors? More lubrication for the shorter skirts??

Greg, do you use the Torco SR-1 synthetic or the SR-5 racing oil? It looks like the only 20w-50 they offer is the racing oil.

There is also discussion in that article of the API/SM spec limiting zinc/phosphorus to 800 ppm (0.08%) but again I am not sure whether they really mean SM or GF-4. What is most often seen is something like "The latest API SM/ILSAC GF-4 category calls for reduced Zinc and Phosphorus levels to allow extended catalyst life yaka yaketa". For most oils they go hand-in-hand but not always.

So can a SM oil with no GF-4 rating (such as mobil-1 20w-50) really have a "traditional" additive package with 1200ppm of the good stuff? Or are they just playing games with spec's?

Cheers!

mark kibort

I use the Racing 20-50 oil from Amsoil.

It will be interesting to see how it works out in the stroker in regards to oil consuption. currently, i would use a quart over a racing weekend. an pretty much nil driving on the street.

mk

Altharos

Hmm I've been running castrol magnatex (sp?) 10W-40, more because it fit the requirements stated in the manual than personal preference....

GregBBRD

Sterling:

How long I run a break-in oil depends on what I use to assemble. If I use any Moly assembly lubes, I change the oil filter after the first hour of running....before I start putting load on the engine on the dyno. I've been using Torco assembly lube for quite a few years, which isn't a thick, black, Moly based product (but certainly contains Moly), so I don't usually change the first oil filter until after the 1st dyno break-in period.

I would not hesitate to run a high end break-in oil for 250 to 500 miles. I don't think that I would run the current Castrol product that long, however.

wds928

Mark:

I hate to be dense, but are you using the AMSOIL SAE 20W-50 Synthetic Premium Protection Motor Oil (ARO) or the AMSOIL Dominator® Synthetic 15W-50 Racing Oil (RD50). I got this info from the Amsoil site and didn't see a 20w-50 Racing.

mark kibort

TRO Series 2000 20-50 racing oil.

Their site and catalogues are confusing.

Mk

ew928

This is the listing page on Amsoil Products that show a TRO 20w-50.
When I click on the link, it goes to their 15w-50 race oil.

Sure hope they know what they are selling.

jcorenman

OK, for anyone not sound asleep I think I found the answer to how Mobil-1 20W-50 can have a higher phospohorus/ZDDP level and still be an SM-rated oil.

First, SM and GF-4 both limit phosphorus to 800 ppm (0.08%), I was wrong about that being just a GF-4 limit. SM is an API designation (API spec 1509), GF-4 is an overlapping spec written by ILSAC (car manufacturers).

Here's the interesting bit: GF-4 only applies to oils in the 0w-30 range (e.g. 0w-20, 10w-30). Our favorite 15w-50 or 20w-50 oils cannot be GF-4 rated. API deals with it differently-- oils outside the 0w-30 range can be designated "SM" and must meet most of the requirements, but the 800 ppm limit on phosphorus does not apply. So voila! Mobil can boost the phosphorus level of the 15w-50 to 1200 and still designate it "SM".

So what else is different between the various API grades? The 928 engine was designed in the days of "SE" or SF", which didn't have any phosphorus limits. A limit on phosphorus was first introduced with SH ('94 model year) at 1200 ppm. SJ dropped that to 1000, SL was the same, and for SM as we know the phosphorus limit dropped again to 800 ppm.

But for all of these API designations the limit on phosphorus only applies to viscosities in the 0w-30 range, no limit otherwise.

So what does this mean for our 928's? None of us (I hope) use 10w-30 so there is no reason to fear the "SM" mark, per se. However that also leaves the ZDDP level entirely up to the manufacturer. I think that all of the oils that we've been discussing here will be fine in that respect, irrespective of whether they are marked "SL" or "SM"-- just look for ZDDP or phosphorus levels in the 1200-1300 ppm range (0.12-0.13%) or words like "high levels of zin and phosphorus".

And Ernest-- it does appear that Amsoil is replacing the TRO 20W-50 racing oil with the RD50 15w-50-- and just in time for Mark K's new motor!

Cheers,