LexVan

If LainM has always been using M 15W50......why the big drop in zinc and phosphorus after the May 2014 change? Did Mobil reformulate again? Further reason to use V-Twin.

IainM

Yes, I'm careful with the start up and have always got moving straight away but driven gingerly for the first 3 miles, below 3k is my rule (til the freeway on ramp - ooh it's hard to resist; but it usually gets to the first mark just off bottom by then -don't know what temp that is) and I don't redline til temp is normal - about 40% up from bottom - then it's open season. This has been my driving style all along - no changes.

I have no explanation for falling P and Zn other than M1 reformulation like you say, PO maybe used high quality oil but I've always gotten 9-10qts out so would have thought P and Zn levels would have tailed off quickly it that was the case.

I think I'll switch to a high P/Zn oil like you suggest and see what gives although 1k miles might take a while this time of year.
Thanks everyone and enjoy the turkey

Steve Weiner-Rennsport Systems

Hi,

Mobil has changed/altered their M1 15w-50 formulations several times over the past 10+ years, even cheapening the base stocks to save money. Each & every conversation I've had with them about this specific product has been unsatisfactory, getting different and conflicting answers each time to the same questions. For me, their integrity has been corrupted and I no longer trust them. I've seen plenty of engines with galled & pitted cam lobes that have been using the 15w-50 oil for a long time.

For these reasons, we will not use nor recommend M1 engine oil with the exception of the excellent V-Twin 20w-50 product which is just fine.

Hilltopper

Once again Steve-BINGO!!

nine9six

I'm with Andy on this one...4 data points (oil changes) is relatively INSIGNIFICANT!

Toss out the high and low in any measured element, and there's nothing unusual here.

To OP...of course keep gathering data...The larger the data group, the more meaningful the statistical analysis.

Steve,
Could you please quantify, "plenty of engines" and "a long time"? Are we talking the past 10 years? ...and for that same period of years, have you been promoting the Mobil V-Twin 20w-50 product?

Additionally, do not the elevated ZDDP's of the Mobil V-Twin 20w-50, also promote premature clogging and efficiency/life of the cat?

...And is there an oil you could recommend, that might be a happy medium between pitting/galling protection and cat clogging?

Yes, I rather replace a cat than cams...But like anyon else, I want it all

Happy Thanksgiving, Rennlisters!

OverBoosted28

This was from last year. We corresponded, and came to an agreement that the high iron amount was most likely from car sitting for months while I was doing projects. All other levels are good. V-twin, always. F, the cats. They do nothing for me or the environment.

NYC993

I would not worry about this a bit. Could be that more copper made into the sample, could be something during the analysis, could be because you added less oil between changes or maybe timing of the additional oil. My copper was at 39 and 26 between two tests. My car had stellar leakdown and compression. Another 993 I heard of also had pretty high copper numbers.

sand_man

The previous owner of my car used M1 15W-50 pretty regularly for oil changes, but I had been hearing conflicting things about this oil's formulation changes over the years. Thus, I went with the tried and true M1 V-Twin, which I used in my 930. As I mentioned in another thread, I'm now running Gibbs DT50 15W-50, which claims to be formulated for "performance air-cooled engines".

IainM

Thanks Steve, I was hoping you'd chime in. Sobering advise - I think I'll change to V-twin at the earliest opportunity.

I'm not too worried about the cats either. Not sure how much they do but I breezed through smog last month. Tech said it was the cleanest car he'd ever tested.

Thanks to all for good discussion.

Steve Weiner-Rennsport Systems

You are most welcome!

Remember, even in the worst-case scenario, replacing cats is FAR FAR cheaper than engine parts.

Dick in TN

Results with 5000 miles since last oil change, using a 50-50 mix of Mobil 1 20-50 V-Twin and Mobil 1 15-50.

nine9six

For my 993, I too use a 50/50 mix a Mobil V-Twin and Mobil 15W-50.

I dont think another data point at 1000 miles is valid for our purpose here.

And in a statistical analysis data set, you usually toss out the high and low data points. In this example, I hardly think the 4 data points is relevant. At the previous oil change, the average was 14; now its 17.

Do another 5k mi. and reanalyze your oil. If you need peace of mind, send in a sample in 2.5k mi.

user 723923490

Is this what you guys are talking about?

nine9six

Yes sir^^^

But this formulation has very high ZDDP's (I believe 1700 ppm), which are known catalytic converter killers (clogging).

Originally the Mobil 1 syn contained about 1400 ppm ZDDP's, which is why I blend 50/50 the Mobil 1 V-Twin, 20/50, and Mobil 1, 15/50.

Mobil1™15W50
Phos 1200; Zinc 1300

Mobil1 V-Twin 20W50
Phos 1600; Zinc 1750