So if I'm reading this correctly, up here in Portland (where it doesn't get that cold, I might want to do something like 20W50 this summer, maybe 40W50 in the winter.

Did I miss the post where the difference between the numbers was explained? I mean 20W is 20 weight (right?); what's the other number.

<noob!

40w50 i dont even think exists and would be way to heavy in the winter. Go with a 10w40 or 10w50 in the winter.

I should try to do this when I'm not at work, I can't concentrate on the other end of the phone and this! :P Thanks Jon.

Razorback, whats your view on Royal Purple oils???

and back to the subject started....

Any luck today? Was the racket of a noise sounding like someone was knocking hard on a door? (rod bearing, low tone) or was it more like some one was taping hard? (valve, higher tone)....... thats as best I can explain it.


Can you isolate where the sound was coming from?

Razorback,

Great info and great thread! I was wondering what your view is on the hoopla I have been reading about here and there on the net about the new (?) API recommendations that result in less zinc in the oil. Apparently this is very bad for motors with flat tappets (like ours I guess) as they depend on the extreme pressure enhancement of zinc etc.

From what I'm reading is that the latest domestically available Mobil 1 (for instance) is very much inferior to that from the recent past because of this. This is something I am really curious about these days...

so that would be why I can use mobil 1 10W30 in my car year round...
still thinking though.. i may change oils next oil change.. just to see what it's like in this car..

its scary though to change from 5w30 to something like 10w40, seems like such a big jump, like a 'shock to the engine'. i have visions of making the change and bad things happening. rocking the boat so to speak. at the same time, i see that 99% of the ppl out there are using xW40/50 oils!! :/

Hmm, low oil pressure, racket, clean oil...at least check the crankshaft pulley to make sure it's tight before you go and take the engine apart.

Gremlin...Everything I know came from Castrol engineers, so what I know about the details of the other brands is just what they have mentioned during our conversations at the track. I will check their web site and see what it says.

20W is the way they express the weight of the oil at 0 F. 20 weight is 20 weight no matter what the temperature.

amjf088, I am not sure if Mobil 1 has changed their oil or not..check their web site and read the 6 vital statistics...that should tell you. I strictly use Castrol and never change brands only viscosity. Zinc is kind of a double edge sword really...it does provide longer protection but it also leaves deposits behind. If the rules are changing about zinc, I would like to read why...do you have any information why they are changing their recommendations?

Mobil 1 used to have these numbers...

________VI Flash Pour %ash %zinc
15W30 170 470 -55 - -
10W30 160 450 -65 - -

I'll try and find out if they have similar numbers.

That's great, I'm going to go to the site right now... if I find new numbers, I'll post back.

IIRC the alleged reason for the formulation changes is for greater eco-friendliness... something we all want, but not at the cost of our engines!

for 10W30:

Viscosity index: 147
Flash p0int: 435 deg. F.
Pour point: -49 deg. F.

No stipulation on zinc and phosphorus.

There is also a good thread going on in the 928 board at Rennlist. It gets interesting on page 2...

http://forums.rennlist.com/rennforums/showthread.php?t=333516&page=1&pp=15

We have really highjacked this guys thread haven't we? Sorry.

amjf088, It appears what you have read is true. Thanks for sharing that information.

Not sure if it was made clear here but I always make the decision based on the engine running temperatures and of course hight RPS's . Our engines run hot. The upper number represents the ability to maintain viscosity at higher temperatures. W30 is more for the average engine that runs at around 180 but we need to use minimum W40 for higher temps so we don't run thin oil.

Thank you.

The people at my garage put 5w30 in my car. I have noticed some lifter noise I think since my last oil change. I never thought that it would be the oil. I might just switch to 10w40. I use 5w30 in my toyota, mind you that is a high revving little ass 1.6 SOB, and it runs cool compared to the 944 engine.,..

It's interesting now that you all mention it. I noticed a bit high temps as well and then this.
In a way I am hoping it is top end related so the repair bill isn't as bad as it could be but I fear the worst. I am still waiting to get my hands on a compression tester so I can find out for sure.
All the info RB and others have posted about oil is great (don't feel hijacked at all) , info like this could prevent someone from experiencing the end result I am facing.

Well, did you check the crankshaft pulley? It's supposed to be torqued to 155 ftlb and it compresses a cone washer between the timing belt pulley and the oil pump. Loose bolt will cause low/no oil pressure and may be the cause of the loud cracking noise you describe.

Just my $0.02.

Checked the pulley, its snug for sure. I am thinking .... is it possible for an oil pick up to drop in the pan?

It is possible the pickup is cracked, typically happens on cars with bad motor mounts or out of alignment balance shafts.

It could simply just be a spun rod bearing. What is the mileage on your car?

Dought the tube would drop in. It's got two large bolts. Cracked??? Use a piece of hose against your blocks and ear. Narrow down the part.