Doug Hillary

Hi,
Mark - Thank you for posting your Used Oil Analysis report from Blackstone Labs

The data you have published is incomplete and to a large degree meaningless as it does NOT include the "serious" wear metals such as chromium, copper, lead etc and silicon is not included either
It is noted though that around a third of the oil has been replaced during your use period

Blackstone's reports are usually very good, I read many of them - would you please post the complete Blackstone report here on Rennlist or send it to me privately.

Only then can meaningful comments be made

Regards

SharkSkin

Doug, any thoughts on my question re: Valvoline?

Thx

Doug Hillary

Ken - Yes an oil with a starting viscosity of 5w has many benefits over another with a 15w or 20w starting viscosity (here we are actually discussing SAE50) and especially at temperatures below about 15C. In any vehicle with hydraulic valve actuation the better flow is very beneficial and the lubricant will come off lubrication system by-pass and oil filter differential by-pass much sooner (see above)
Mobil's 5w-50 (the ONLY SAE50 oil Approved by Porsche) has better flow characteristics than what you are using but is not available in NA as I understand it

Generally Castrol-BP lubricants are excellent although much of the Castrol "history" has sadly been replaced by BPs
Ken, your choice will do you well!

Dave - Valvoline are not too free with serious technical data - sad that. A bit like Redline and Amsoil!
I have checked out another similar Valvoline product and its HTHS viscosity was confirmed by their OZ "Engineer" as follows;
"We do have specific measures. However we use a quality polymer that will easily exceed the SAE 3.7 standard"

This sort of "practiced" comment always concerns me - especially in the absence of "hard copy" to confirm it

Porsche's minimum for HTHS is 3.6cSt as I recall

Valvoline do make a number of Porsche, BMW and MB Approved oils. Always ensure that the ACEA A3/B3 specification is stated on any oil going into a 928 engine!

Matt - I would NOT use the 5w-30 version of Mobil 1 T&SUV as the HTHS viscosity is only 3.09cSt - a long way below the Porsche minimum specified.

I would like to comment on other Posts on here but will wait until Mark publishes the full Blackstone Lab UOA report

Regards

FlyingDog

There is no way I'd use it in the 928. I was posting it as a comparison. Temps and milage increased going from 40 to 30 in the Jeep, they may do the same going from 50 to 40 in the 928. Although it could have also been the change from Rotella T to Mobil 1 T&SUV.

Mark and Glen, the temp guage was ALWAYS directly on the mark at 210 once at operating temp except when sitting in traffic for a long time above 90 or 95*. It did matter whether I was moving, the A/C was on, I was offorad climbing mountains, it didn't matter. Now when moving, the is a needles widthe between the needle and the mark. The temp has dropped. Mark, the needle position could only go up if the thermostat was pegged open like you say. If the thermostat was closed, the needle could go down. The thermostat opens from excess heat, not too little heat.

Doug Hillary

Hi Matt,
Sorry I misread your comments!

Some engines do rspond to oil type and viscosity as you describe. You have made a very significant change from a robust and excelleny diesel/petrol Group 3 5w-40 lubricant to a very advanced formulation Group4/5 5w-30 lubricant
It is possible to get such variances as you describe - many factors in the engine's design dictate that
You have made a great selection - we cannot purchase that oil here in OZ

Fuel efficiency is influenced by oil selection - there is a huge amonut of data on this very complex issue. In a change like you have made efficiency is likely to be improved I expect at idle and lower revs and at steady state running

Regards - and again sorry!

FlyingDog

Don't worry about it. I was not clear in what I typed in the first post. Thank you for all of the information and recommendations you post.

mark kibort

thats why i said that it wasnt impossible, but was, more than likely, improbable.

Im no expert here, but a small percentage weight change of an oil, which is some percentage of the heat generated inside the engine, most being that of combustion, as you say, would seem like a lot to ask or expect from just a change of oil.
my main reason for using amzoil is for more confidence in its thermal breakdown charateristics, and other mysterious protective qualities.

I get your point about the heat of the larger, more powerful engines really not tranferring its heat in the heads, but moved out the exhaust at a rapid rate to avoid the heat transfer in the engine.

Mk

mark kibort

Doug, no problem. I was alwasy curious, but not worried, since the oil filter is so clean when taken apart, and engine seems to be running very well, even after 5 years of serious abuse!

Ill email you the oil test results. its in PDF and didnt have a way to post it. that i knew of)

by the way, the race car uses about 1/2 quart over a weekend, so i figured over the past 4 months or so of driving and racing , that there was a total change of 3 quarts. considering how many rpms over the 3500rps my engine saw, i would say that 3 quarts really equates to 12,000miles of normal driving, if you understand how ive been using the engine. (exposed to 270F oil temps for hours a weekned, etc)
silicon normal is 6, holbert car scores a 5
chromium normal is 3 , holbert car is 2
Aluminum normal is 5, holbert car is 6
magnesium normal is 518, holbert car is 220
copper normal is 4, hobert 2
lead normal is 2, holbert 2

How does this stack up?

Mark

Doug Hillary

Hi,
Mark - thank you for sending me the complete Blackstone Lab used oil analysis (UOA) report
Your UOA suggests that all is "normal" as they have stated - my comments for what they are worth follow

Comments on the UOA:
Wear metals: all wear metals are low and at "normal" wear rates for a 928. The balance between wear metals is maintained - again "normal" but an indicator of the engine's good health

Additive package: the chemicals measured indicate a good level of protection remains
(paying a little extra for a TBN/TAN measurement in a UOA is worthwhile)

Oil condition: The oil has lost viscosity and is now almost a "borderline" SAE40 lubricant. This is a little unusual as Amsoil products usually become more viscous (thicker) which is undesirable. Bearing in mind the engines use and the top up volume it is a little concerning but probably quite normal

All in all Mark this is a "normal" performance

Many oils of a similar type would perform the same in this environment - Castrol's "R" or "Edge" 10w-60 and Motul, along with those from other Oil Companies (Shell, Mobil, Valvoline etc)

Some other comments;
1 - "Universal averages" of course depend on the number of UOAs averaged and I expect that Blackstone would not have very many 928s on their Database. With this in mind I can comment that my own Database averages for 928 UOAs put most figures at a higher level than theirs. However it is a little academic as we are only "talking" about a few parts per million (ppm) in variances
Measuring your level of wear metal uptake compared to my Universal Averages, all is about "normal"

2 - It is almost impossible to measure one oil against another in terms of wear performance unless you use the likes of Radioactive Tracer Technology (RATT) and measure real time results in Nanometers (one millionth of a mm) per hour.
You cannot do a meaningful wear comparison using UOAs

3 - UOAs can tell how an engine is wearing (once a UOA history is established), the level of fuel, coolant, water present, and the "condition" of the lubricant in an overall sense

4 - Many times "severe service" is used to describe oil use conditions. There are a significant number of variances here but one thing is known - keeping a synthetic lubricant at around 90C and up to 130C is much better than running it where it never reaches that temperature - all things being equal
A 928 in normal use has a core oil temperature of around 93C and a oil cooler thermostat that is fully open at about 100C

Should we continue this thread on Oil Pressure versus Flow and the effects of Temperature and etc ?? You as readers decide!

Regards

SharkSkin

I wonder what the lab would have said if Mark left one of his broken cam-sprocket teeth in the sample...

Doug Hillary

Hi Dave,

Blackstone Techs may well have said "I thought this was an engine oil sample - not diff or gearbox oil"

Regards

mark kibort

Doug,

Thanks for the report!

Sounds like all is good, and the oil still has the protective elements , but the viscosity is on the low side. interesting. I really think the way im racing the car with the rpm and extreme heat, that its probably normal. it would be interesting now to see the tests of mobil 1 used on the track. not just DE events, but 10 or more race days!

Since I told blackstone that the oil is 3500miles, but its mostly racing, i would say that at least 50% of the miles are at 4000rpm to 6500rpm. so, since most freeway driving is at 70mph and 2000rpm, the 3500miles is more like 12,000miles


Mk

Doug Hillary

Hi Mark,
many engines operate in that rev band - in fact it is the prime operating band for many Euro and Asian engines

Heat is a subjective issue in engines amongst many owners - and "base" oil temperature is a complex matter. A good synthetic oil will have no difficulty operating at up to a 130C as a base temperature - localised temperatures are much higher of course

I operate two engines where localised 140C figures are normal and the base temperature is around 120-125C
The oil cooler in a 928 seems to "wash away" high temperatures very quickly IMHE

As mentioned in another thread on here the 928 has a very good engine cooling system indeed.
It just needs to be kept in good order

Regards

mark kibort

Doug,

You know thats not the point. I think its more a matter of runnig the engine at max output. a honda s2000 could operate at 4000rpm, less than half its redline, just as it would be like 3000rpm for our cars. the real point is the effect of running a particular engine at 100% of its capacity, (WOT) for most of the time. I spend more time at full throttle in one race day, than most cars see in their lifetime. ever do a 60 -100mph run? it takes only 7 seconds in an S4. flooring it from 60 -80mph, try more like 3 seconds. 50% of a 30min race is with the pedal to the metal. thats over an hour of full throttle every race weekend! 60 min of full throttle, thats 3600 seconds. think of it like taking your car and doing 600 dyno runs! oh, and by the way, do it every single month!

some of the cars that run 24hours of lemans change the oil at least once during the race. I wonder why that is? I bet they have found that the oil looses something with that kind of abuse.

anyway, i think youre right about the 928 cooling system. its pretty darn good.

Still interested in how other oils stack up as far as viscosity at 280F and what the wear numbers look like after racing for a few months of racing.

Thanks again for all the information. interesting stuff. keep it coming!

Mk