Fabio421

Of course you will see an increase in oil pressure if you increase the weight of the oil. And you will also see the inverse when going to a lighter oil. I use Mobile-1 0w-50 ( or maybe its 0w-40 I can't remember) and have seen the same thing. If the WSM from Porsche says 1 bar why would you question it? Are you saying that you are smarter than the engineers that designed the car? A lighter weight oil will lubricate better at start-up and will flow easier into tight spaces. Most wear is at start-up. I'm sticking with the 0w-50.

stealth

At the risk of turning this thread into a brake rotor debate , those seem like a good price (and they're practically local to me, so no shipping, though would have to pay sales tax), but I've read many posts wary of the use of cross-drilled rotors, especially ones that were drilled rather than cast. These were drilled by the company selling them as opposed to cast that way by Zimmerman. Isn't it the case that drilled rotors will crack much more easily than plain and that if you want the vent holes you should use ones that were cast that way, not drilled post-manufacture?

I suppose for street use the stress may not reach the point of cracking them (and who needs pretty zinc ones for the track). Maybe I should get some for the 86.5 but not the GT, for instance.

Thoughts or experiences?

cfc928gt

Stealth, what makes you think these are drilled and not cast? Zimmerman makes cast cross-drilled rotors. I agree drilled aren't as good as cast.

SwayBar

This is perfectly normal.

I've never seen that behavior before; there may have been 60W in there.

According to the workshop manuals, VIII - 0.25, for Engine Oil it states:

"Quality HD multigrade oils to API classification SE or SF according to plant approval list."

Note that Porsche did not give a specific viscosity range like they did in the past for their earlier motors. As you already noted, Mobil 1 is Porsche approved, and Mobil 1 0W40 is factory-fill for their cars. Mobil 1 0W40 also has the highest European B3/E3 shear-strength rating versus the lower shear-strength B5/E5 Mobil 1 10W30 and 10W40.

Hot, both are 40 weights; the only difference is that your 0W will flow better when cold.

No way, save your money. Next time, regardless of viscosity chosen, make sure you get the B3/E3 rating as you did this time with the 0W40. I know that Mobil 1 20W50 is B3/E3 rated too.

drnick

hey mark, what kind of car was that porsche engine you saw toasted in? i dunno if that necesarily means mobil 1 is no good or if it just means that racing is a harsh environment for engines and some of them will let go. especialy when you consider that mobil is the oil recomended by porsche it seems reasonable to think that more cars will be running with mobil and therefore you will see an apparent asociation. otherwise its just as reasonable to think that porsche engines are bad cause youv seen more than one melt at the race track..

stealth

I went to the seller's website. They say that they machine them themselves and "pass the savings on."

So, they buy plain solid rotors from Zimmerman then drill them and zinc plate them.

Definitely Zimmerman makes cast ones, but I don't think this place is selling cast ones.

Doug Hillary

Hi,
Mark
you consistently blame one oil for every engine failure ever - it gets a bit boring actually. You never back it up with facts and detail! And what about the engines that DON'T fail on THAT oil????
Over the years you indicated that you would provide UOAs on YOUR Approved oil - sadly they have never appeared on here!!

You once had an engine failure when using M1 10w-30 as I recall - an oil NEVER Approved by Porsche or recommended for use in a Porsche engine!

Fabio & Swaybar - good stuff thanks for your excellent and accurate input

Oils of 0w-40 and 5w-40 are Approved and Listed for use in our engines - the only SAE50 oil Approved is M1 5w-50

There are many excellent Porsche Approved and Listed oils available. No research has shown that any Brand meeting similar specifications will perform significantly better than another!

Oil pressure on a 928 at idle should be somewhere around 1-3bar at a HOT idle (after 30mins running). Typically above about 2000rpm you should see 4bar and you must see 5bar over 4000rpm
An oil that is showing 4 to 5bar at a hot idle may be providing too little flow at 4000+rpm

Regards
Doug

IcemanG17

Bill
I just have too many perfectly good rotors to invest in a purely cosmetic setup like this one......However....they sure look SWEET......I just picture them with my wheels...& drool..... Must not buy....must not buy

:>)

Marine Blue

Brian those rotors really do look sweet. Hard to say what type of plating is on their but why lie? Personally I would take your existing fronts, remove them and have them bead blasted. then I'd send them with your new rears to have them plated. They'll look even better than those on ebay, trust me on this! The nickel truly holds up well when cared for and I'm not joking when I say this, I did canyon runs on mine regularly without problems.

Regarding the oil weight I guess I'm a bit confused as I'm reading varying information. I was suprised at the lower pressure considering the operating viscosity states 40, I didn't think it wouldt be all that different. My only thought is that maybe my old oil was a 50W at operational temps which explains the higher pressures.

The lower starting viscosisities are typically better for most cars as the pump can get the oil moving faster....BUT I've heard that on some cars the viscosity helps keep the oil on top of the engine and lubricate it during start up where as the lower viscosities drip through and settle leaving nothing on top for lubrication. Two schools of thought and I guess it depends how this engine works on startup.

Either way I will switch to Amsoil since I've had better luck with it but I will probably let this oil stay unless it gives me problems. Hate to let all that oil go to waste.

mark kibort

It was a 944, and he toasted the #2 bearing.
Mobil 1 seems to be a common denominator for many of the porsches ive seen grenade.

For some reason, i beat up mine others are being beat up as bad, and with different oils, they dont seem to fail as often. Yes, all race engines will toast eventually. however, id prefer, later than sooner. One thing ive seen is low oil pressure with mobil 1 vs kendal 20-50 racing (anderson uses and i used to use) and redline or Amzoil. when the oil pressure warning light comes on, the oil has lost viscosity. probably never an issue for street driving, but if you occasionally track your shark, i would advise against mobil 1.

Mk

Larry928GTS

And he also completely ignores those engine failures that have occurred in 928s that were using those other "boutique" oils.

mark kibort

Here is a fact for you.
120 track days, no #2-6 bearing failures. Near redline , 1000s of times
punishing races at near 100 degree temps, oil temps in the 260-280f range, high g loading turns, and several engines that never had an issue.

compared to Hanson, Shaw, and the countless others that have raced less often and have blown in months of rebuilds or of the beginnings their track activity. the common denominator, Mobil 1. thats enough for me!

Now, just because porsche recommends it............. please, if you know anything about corporations, and partnerships, its easy to see how porsche recommends mobil 1. its great partner marketing. as we all know, for street use, there are very few differences between oil, gas, etc. yet foks swear by their cheveron gas, and their mobil 1. Where are the extreme conditon testing? They are done on the race track. Im sure there are many race engines that could be lubricated by baby oil, and others that need an oil that doesnt break down or loose vicsocity. If mobil 1 is so great, then why are so many race times not using it, and why is there a market for these "super oils" that cost 5x as much. I think there are some racers that use Amzoil and redline because of their lubricating qualities under extreme conditions.
airplane racers with engines far exceeding the costs of any race engine, are using oils other than mobil 1.

for many, its a little religious. For me, its about 50-50. i kind of buy into the shear tests and other tests from independent labs. but the most important facts were the oil pressure light repeatedly coming on for lack of pressure during a hot track day run vs other oils that didnt show this kind of issue.

I was running the carrocel at Sears point yesterday, and was noticing over 5 bar general pressure, even near lap 15 of the race, almost redlining every shift, and down this carrocel, at 5krpm, 7 seconds seeing 1.5 Gs and oil pressure still near 5bar.

amzoil for me, but that my own opinion. yes, not scientific, emperical.

let me know what i need to do with my oil to send it in. how much, where it goes, etc. I just havent changed it in a 3 races. but after this next race, i will change it and send in the sample to see its characteristics.

I also see 3.5bar at idle. hot or otherwise. at 2krpm its at 5bar

by the way, i never had an engine failure, ever ! and never used 10/30 M1, so you may be confusing me with someone else. scot's used engine failed, but it also had 1" of sludge in the oil pan before we tryed to race it and it siezed. look like the tiny holes in the #2/6 crank were clogged.

Mk

mark kibort

I just havent heard of that many of them. what 1 or 2?? related to something else? there were a barage of failures and many were using mobil 1.

again, my ONLY basis for my choice is using mobil 1, hearing about many other oil related failures (or lack of oil ), and seeing the pressure differnces on race day. other than that, i have no scientific proof or information. thats all . no more no less.

MK

Rich9928p

Mark,

I've seen several 944 throw rods at events and they were using Amzol and Royal Purple - and I don't go around trashing Amzol (although I hate their marketing strategy and the goons that push that stuff). Racing engines blow up for many reasons - not just oil. Many hoakey racers take an engine with unkown service and high miles and just go out on the track and risk everyone's life when they blow a rod and dump oil all over the track or blow a hose and dump antifreeze in corners - as a minimum when buying a race car rod bearings and hoses should be changed before tracking a car. To blame all engine failures on one type of oil has no factual backing ... just superstition.

This guy isn't a racer - he is very unlikely to experience the g-cornering at > 5500 RPM that is associated with 2-6 rod bearing failure.

Here is a fact ... the earlier Mercedes had oil pressure gauges that only went to 3 bar. In the mid 80s when I was in Germany visiting Mercedes Benz I asked an engineer why Porsche shows 5 bar and they only show 3 bar on the gauges. He said there were too many customer questions/complaints so they just changed the scale so it would always show at the top .... happy customers and nothing else changed.

deliriousga

I switched to Mobil1 0w40 too when Porsche recommended it for all post '84 models. The engine runs much smoother than it ever has with the clicking noises going away, but the oil pressure did drop at idle to about 1.5 bar.