Macca

Did you mean Mobile 15-50 here?

I have flat tapped (backdated with SS cam) and wonder if this viscosity may be better than the 5-50 CCS put in my car at service time...

nirich

Definately Mobil 1 5w-50 has the most ZDDP. It appears there have been several 964 rebuilds over the years in which cams have had what looks like a touch of oil starvation or pitting particulalrly cylinder #6 and i do wonder if that is due to the missing ZDDP. As i said Brad Penn has the max ZDDP with the bonus that it is nearly $100 per oil change cheaper than Mobil 1.
I too have a set of Dougherty 993SS cams ready to go into my car one day.

Cheers,
Nick

PS: I run Mobil 1 in the coupe (about to change to Brad Penn next oil change) and Brad Penn in the Targa.

Macca

Nick that really interesting. My car had the cam replaced at 70,000 km. The car has been run on 5w-50w for as long as the product has been available (15 years+). Here's some pictures from the tear down. there was no discernible wear on any of the head components after 17 years of use. Maybe I got lucky!

PS. The fresh cam next to the worn cam is the 993SS.

gt38088

I'm no expert on oils but the feb 2013 Excellence mag had 2 Q&A points in Tech Notes - both interesting and related to the issues discussed here.
1) Boxster owner uses Mobil 1 0-40 year round asks if he should use different weights summer - winter. Answer. (summary relevant points only) recommend 5w-40 year round Motul 8100, or similar boutique oil. ZDDP additives (high pressure) are being reduced in many oils today, resulting in more wear esp in mechanical systems like valve train. target ZDDP should be preferably above 1350ppm
2) Q - punter has been finding if difficult to fid mobil 1 15w 40 can he use 10w 40? Answer
a) recommends again motul or a group 5 synthetic oil over a 'lesser' group 4 synthetic like mobil 1.
b) the American petroleum institute classes synthetics into gp 4 and gp5
c) Gp4 oils are made from polyalphaolefins (PAOs) which are chemically engineered synthesized base stocks offering excellent stability ad molecular uniformity - mobil 1\
d) gp5 also synthetic base stocks but also esters made from vegetable, mineral and animal fatty acids (motul and redline common is the usa) Gp5 has all the advantages of PAO but more. Burnt esters leave less residue from oxidation and thermal breakdown. Gp5 also more thermal stable, less detergents meaning less friction, and also less deposits. Higher thermal transfer properties means these oils are better for air(oil) cooled engines - up to 10% increase in thermal transfer between metal parts and the oil.

There you go - just summarizing

Macca

Great info. Im wondering which Motul product is best for our mechanical rocker engines (assumes track use)? There seems so many choices on the Motul site!

gt38088

They seemed to be recommending Motul 8100 I'll check tonight to see if the grade was different for aircooled vs water

Macca

Hi Graeme. I did some research last night and the 300v 15-50 seems to be be the ticket. At $145 per 4 litres with a 11+ liter need its almost twice the cost of Mobil 1 in NZ! I suspect this is worth the money once youve done a big engine upgrade/rebuild. However for regular running I expect its beyond most peoples budget! Its definitely recognised by most Porsche race engine builders worldwide as THE BEST full stop engine oil for the aircooled flat six with mechanical lifters. Id like to try it but perhaps one day in the future (just had fresh oil in Feb)...

John McM

Well [deep breath], the look into my gearbox has found the following. This is a version of the same issue Jason had/has. I'm exploring options now. There is no evidence my car has been tracked and Dean just told me the other two he saw were normal road cars. Peter, sorry to upset your day, but I don't think this is an area any 964 C4 owner can ignore. You don't have to run your car hard to have this issue.

Macca

John. Really sorry to hear this. Its the last thing you need right now. A cracked carrier is a major problem about to happen. Looks like the pin was on its way too. Given the age and miles on these C4s now this looks like an increasingly likely issue. For this reason I cant see finding replacement parts getting easier or cheaper. I hate to say this but I think the move to making the car 2WD is now almost a foregone conclusion. Even an effective repair will not be a guarantee of future durability on the track given you will start to increase the loads as you get better and faster. Unless there are some alternative reliable solutions it seems in many regards the decision may have been made for you. I feel your pain!

peterC2S

Wow. Is that the only part damaged - ie. before it had the chance to shatter and cause a worse outcome?

Need to post on the 964 board and refer back to Jason's thread also. I don't think its scaremongering given the circumstances.

When you're talking to Dean next could you ask him what the straight cost to drop the engine/trans and do the pin weld would cost? Assuming no other damage and no other work to be done - ie. purely preventative.

That sucks mate. Surely there's nothing else to be found now?!

peterC2S

Cogs Cogs has these used - not sure if Jason has pulled the trigger first though in case there is only one!

http://shop.cogscogs.com/Distributor...-10_c_715.html

item #27 US$1,700 new or $700 2nd hand

John McM

Dean hasn't identified any further damage, although I have sent him a picture of Jason's damage, just to show him what happens elsewhere.

I've got on my largest pair of big boy pants right now. Let's be clear, the issue appears isolated to the pins coming adrift and damaging other parts. The solution is to weld the pins. If the crack is all I have, there may well be a way to weld or pin it. I'm not a metallergist so I don't know the relative strengths of those. I may well have to just replace it.

Peter, I will check for you

kiwi 911

So looks like the 64T then for gymkhana and play day??

I am told my car will be ready for the end of the month??

John McM

Yes, the "show pony" is looking like the best candidate for the Gymkhana. As for the Playday I'm out until I have my C4 fixed. However, don't count me out too quickly.

Good luck for your car.

John McM

Dean just confirmed that there is no other damage.