FeralComprehension

This is the synthetic Rotella, 5w40, ~$20/gal at Walmart.

I'll keep using it, and stay with a 15,000 mile interval.

Note that the total consumption for the interval is 4qt (not 7). The oil was not changed after I sampled it the first time.

ETA: Link to first sample thread.

ryanowen

Very good info. Walmart Rotella it is. Thanks for sharing!

FlyinTomato

Ive been using rotella on my motorcycles. Vtwins, Didn't know these are good with our cars too. Good stuff

misteralz

That's a very good lube oil report, very good oil and one healthy engine. Depending on cost, I'd be tempted to get a report done every three months or 5k miles rather than change the oil every year/10k.
Is there a second page with trend graphs? Most of the oil reports I deal with have that - it's really useful for tracking machinery degradation/oil deterioration/additive depletion over time. If not, you could easily do it yourself in Excel.

misteralz

Oh, and just out of interest - how did you sample it, and are you doing the same for the gearbox and diffs?

FeralComprehension

There is a trend graph but with two samples it was too boring to include

On this car I get the oil hot and put the sampling tube down into the tank while the engine runs (I bought the sampling pump from Polaris; works pretty good).

I don't like to change the oil on this car, or adjust the valves (total PITA imo), so the main reason for the analyses was to verify that I can get away with a 15k change interval. Given how the car runs and it's oil consumption (15,000mi/4qt=3750mi/qt (and it leaks, I park on cardboard!)) I think 15k is going to be fine.

The other reason I got the analyses is to ensure that I'm not hurting my sled using cheap Walmart oil

misteralz

Ideally you want to be taking it from the oil that's circulating, and preferably from before the filter. If you can't do that, then a dip tube in the tank's a good compromise. Looking at those results so far, I'd be tempted to change the filter every six months and just top up the level as necessary, rather than changing out the oil charge completely - but obviously I'd be sampling it regularly!

In case you were wondering, I'm a reliability engineer in the oil industry, with a background in rotating and reciprocating machinery - I've had to make recommendations on results like that before, I'm not a total novice.

misteralz

Oh, and cheap WalMart oil will just be last season's Mobil Super Extra Spafftastic 5w50.

FeralComprehension

Thanks for the input. Given the flow rate of the oil pump, so long as the oil is hot and the car is running I'd think that tank-oil is circulating. With respect to the rest (filter change, 6 month sample schedule), what do you see that would justify that? The filter on these cars is quite large, and there's no evidence (that I can see, anyway...) that a filter change would improve things.

I dunno.... In my mind this car will get a rebuild of some sort in the next 50k miles, so the additional effort and expense just isn't needed given the solid performance shown in these analyses. Am I missing something?

ja78911sc

Your Phosphorous is low. The Zinc looks good.

Keep in mind that the new diesel oil formulas have less PH because of the 07 EPA emission standards on diesel engines. This emission standard was met with the addition of a diesel particulate filter (DPF). PH was lowered because it can damage DPF filters--similar to high levels of PH damaging catalytic convertors on cars. CI-4 plus is a pre 07 emission diesel oil. It is very difficult to find on store shelves. Chevron is one of the few that still manufactures CI-4 plus.

misteralz

The fact that you've got very little debris in that sample shows that the filter is working - but you can't test dP across it or anything to see how well it's performing over time.
How much are Polaris charging you per analysis report? How much is 11 litres of Rotella? And how much of a pain in the **** do you consider an oil change to be, and how much is it worth to you not doing that? Over here, I'll pay £12 for a sample report like that and £10 for a filter. Mobil 1 is £30 for 5 litres from Costco. So, yearly oil changes (assuming I do them myself) are ~ £70, plus the hassle factor. Six monthly samples and six monthly filter changes come to £44 - and if the oil's still good at the end of that time, like yours, then yay. Sure, at some point you're going to have to change your oil, but judging on the current rate of deterioration, that isn't going to be anytime soon.
Obviously there are bigger gains to be had with a larger oil charge, and you wouldn't bother doing this with your shopping car, but it's an interesting exercise and one that looks worthwhile for 964s.

911Jetta

15K change interval...and I worry about changing my Brad Penn oil every 3-5,000 miles.

But at 150,000K it still feels very strong, and I don't hope to ever have to rebuild it. (it had an engine reseal just before I bought it at 100,000K)

Given the expense it's obviously not something you've do on a whim, why do you see a rebuild coming?

ja78911sc

Maybe you will be this lucky This guy is my hero


richardew
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Someday I may get some work done to the engine.
I think that I may keep this car. It's still fun to drive. It has a multifunction steering wheel too. It steers and honks.

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LexVan

I don't know. That UOA looks aweful, IMO. Your copper and lead are sky high. On my aircooled car, those same levels are 5 and 7. You should be changing your oil a lot sooner than 15,000 intervals. And considering you've added 4 quarts of make-up oil during that interval, diluting the actual wear metals, seems even more alarming with your 15K mile protocal. Oh well.

Why are you running a 5W40 in an aircooled Porsche? Your 100 degree cSt viscosity is low too. You want to see values in the 18-20 range, and you would if you used a proper 15W50 or 20W50. Then your zinc and phos. will elevate too. All good.

FeralComprehension

Not according to the laboratory they're not. Not according to other reports I've looked at they're not. Were your values at 15,000 miles?

You mean like the 12,000 miles the owner's manual recommends? Why should I change the oil if it's in-spec and the wear metals are within tolerance?


Because the car gets used year round (as they're meant to do).

Umm... it's in spec, and 40w is Porsche recommended for summer use in this car.

Based on what? Again, Porsche say 40w is fine and the lab results show solid performance.

You may be correct.

It leaks oil, and at 175k (?) I'm not going to tear it down just for a reseal. Plus I'd like a little less reciprocating mass and a little more go. Nothing too rad- lightened parts, updated engine management, full balance...