Originally Posted by Andy916

Yes, get an oil cooler. Before your next trackday.

Oilman replied to you saying a good oil is fine up to 150C, but that's based purely on the spec for a virgin oil ie. freshly changed before the trackday. The reality is that you get fuel dilution on an Impreza, especially a tuned one, which degrades the viscosity of the oil and impairs its high temperature performance. This is because the fuelling is a little uneven between cylinders, so the mapper makes it safe across the board. The result is that the fuel consumption isn't great and the oil suffers fuel dilution over time. In addition to fuel dilution, oil loses its viscosity with use due to shear forces in the engine.

Ok, here are a couple of real examples from a 360bhp classic with an oil cooler (max temp 100C). I had Millers analyze 2 oil samples. First up, Motul 300V 15W50 which had done 2-3k road miles plus 1 trackday (approx 100 miles on track). This was down to 79% of the viscosity on the spec sheet for virgin oil. Second was Millers CFS 10W60 after 2-3k road miles plus 2 trackdays (approx 200 miles on track). That was down to 75% of spec sheet viscosity. Millers tech guy deemed both viscosities to be "on the very low end of what is acceptable".

In case you're wondering why I did the oil analysis, previously I blew the big-end bearings on a trackday. The damage was almost certainly due to a combination of high temperature and slightly too old oil: 130C peak (this was before I got the oil cooler fitted), on CFS 10W60 which had done 4k road miles plus 1 previous trackday. Previously I had kept to 3k road miles with a max of 2 trackdays, but on that occasion I slipped up and paid the price. After the engine rebuild, and oil cooler install at the same time, I was keen to see how soon the oil degraded with use. The answer is that, in my engine at least, the oil viscosity is almost exhausted after 2-3k road miles and a max of 2 trackdays.

So, T20Driver, how often do you change your oil? And have you got an oil cooler yet?

Originally Posted by dunc1055

Hi Oilman

I have been reading this thread very useful info here.

I have a 03 reg wrx sti type uk 6speed box standard, I realise i need 75w-90 but which, i want to crisp-en up the gear changes from cold as changing down in to 2nd and 1st can be a bit notchy. I was told about redline shock proof, is it this:

http://www.opieoils.co.uk/p-1022-red...il-75w-90.aspx

This says not recommended for most syncro-type transmissions, im confused

Also which syntrax the universal or the longlife.

Does my vehicle have any form of limited slip diff, i assume the rear diff takes same grade.

Also the garage that last serviced my vehicle from previous owner put 5w-30 performance oil, according to the invoice this seems a bit thin???

Sorry for all the question thanks

Thanks

Originally Posted by oilman

Hi

The Shockproof oils are fine with synchros, we've never come across anyone who has had a problem with the Shockproof in a synhcro gearbox, and we sell loads of it. If you're having cold shift problems, the Shockproof wouldn't be my choice as it's a little thicker than standard stuff due to the way it works. I think I would go for the Motul Gear 300 as it always seems to work well in an Impreza.

http://www.opieoils.co.uk/p-899-motu...ter-based.aspx

That's fine for the diff too. It does have a LSD, but it doesn't need a LS specific oil.

If you want Castrol, it's the Syntrax Universal, although that is a couple of steps down in quality from the Gear 300.

A decent 5w-30 is fine for a standard car, but if it's driven hard on a regular basis or is modified, a 5w-40 is a better option.

Cheers

Tim

Originally Posted by Sub-Subaru

Subaru Impreza WRX Uk model, 2004, 2.0 turbo, 80,000 miles.

Currently standard, but might possibly do a basic remap in the next year or so.

Currently it is my daily driver covering 44 miles a day. Might soon become only used for shopping trips and weekends. Not really driven mega hard but is used properly

Looking for good quality engine and gearbox oil recommendations, price isn't really an isssue just after good quality that will help the engine as much as possible.

Originally Posted by steviechi

Impreza WRX but with TD05-20G, 650cc injectors and Sportscat exhaust etc 360bhp

Daily drive - 15 mile each way, gets thrashed in the middle - allowed to warm up and cool down. Road use only

Car has 110,000 miles on the clock

Recommendation for Engine oild and gearbox oil (is Slick 50 gearbox additive any good?)

Thanks
Steve

Originally Posted by Donnie Brasco 46

Subaru say 5w/30 but most people on here tend to use 10w/30 or 10w/40.

I'm getting Subaru to service my impreza soon - I'm already wondering what oil they'll use.

Obviously fully synthetic is better than semi/synth. If money us no option I'd go Mobil one or the top gold castrol cos then you can't go wrong. I hear things about millers but yank oils just aren't the same in my humble opinion