10w50 or 5w40 for sti engine running 400bhp ?
 

I've been using Silkolene Pro s 10w50 in my classic sti engine for a while but after speaking to Opie oils i've ordered 5w40. The reason for this is the car is used everyday to and from work and the 5w40 will give me better protection from cold.

After reading a few posts on here i'm worried that 5w40 maybe too thin !

Anyone got any ideas if it'll be ok for me ?

got my car remapped by jgm other day an mine got 300bhp. i asked wot oil to recommend as more heat an said motul 15w-50. hope this helps

Personally I think the 5w-40wis fine and is what I use only running 340bhp tho but there are some very high grade oils about that will cope easily.
If you are still concerned how about running the 5w-40 in the winter then changing to the 10w-40 in the summer :) every ones a winner :D

I'm just worried that 5w40 is too thin for these engines but if other people are using it then I think that it should be ok.

i got 10w in my car at mo but going to go for 15w as the engine is gonna be running hotter. 5w is good for warming up quickly but just warm your car up that little longer and will be fine

my 2006 sti hand book recommends 5w-30w so if Subaru are saying it that's good enough for me :notworthy

On the other hand i've been told that a 15w is too thick !

I don't want to start another massive oil thread as there's been enough of them :rolleyes:

The thing is, 10w is the cold end, When cold the thinner the better, Flows around the engine more quickly, Once hot & using 5w40, You have the whole spectrum upto 40, so you are protected from 5 upwards Etc...

Dean

Yep,that's exactly what Opie oils said to me :thumb:

So the next question is will the 40w be good enough to cope with the heat associated with running the power that I am ?

If your tracking it hard all the time then the millers 50w might be more suitable but for fast road 5w-40 is fine :thumb:

I cannot remember what the Temp is that 5w40 starts to break down/shear but opie will tell you im sure, I also think that if your oil temps are exceeding that, You really need to invest in a futher External Oil Cooler !! & i doubt that is the case, I was running 330 /300 on a classic for best part of 30K miles, No issues.. You really need to know what your Oil temps are, That is the concerning factor ..

Cheers

Dean

Oh yeah I think the easter based oils are the ones to go for.

I've just fitted a set of gauges so will see what oil temps are like.

The "W" refers to the cold performance end of the grade, so you won't get a 40w - that would be like treacle when cold!
If you don't want to be bothered with changing from one grade to another from winter to summer, then a quality 10w/40 such as Millers CFS will be fine all year round.

JohnD

Sorry,meant w40 !!

It's not really the weather that's the issue. It's mainly that within a couple of minutes of leaving home i'm on the motorway and the same when leaving work. Just thought the 5w would give me better protection than the 10w that i'm currently using.
The cars pretty loud so can't wait around for it to warm up before leaving !

Hi mate I just serviced my classic impreza turbo 2000 103k on the clock with silkolene pro s 5w40 ester based oil based on opie oils recomendations.

the car runs fine but I hear more noise now so i think Im gonna change to a ester based 10w40 dont think it will matter much to me 5w40 is a bit of overkill in my std engine and we dont really see thetype of cold temps to benifit from using a 5w40

so a 10w40 ester based is next on my list and should be a good compromise between the 5w40 and 15w50 think im gonna use motul v300 ester based for the win. Its a bit more expensive but we are prepared for the cost when u drive an impreza!

was told by a racer that on the sti engine with over 50k miles you want 10w 50 semi. didnt ask why just assumed its slightly thicker

I used to run 5w-40 silkolene pro s in my 95wrx , found it a bit to thin and had more engine noise , now run same oil but 10w-50 , runs well and oil temp rarely goes above 90

Right,I have no idea whether to put the 5w40 in my car now or not :mad:

Opie oils definately recommended it to me after asking what mods/style of driving etc and bearing in mind it's not tracked.

give it a go if you want mate all im saying is in my car with high miles I wouldnt recomend it in theory sounded good but hearing my car since the oil change its worse.
10w40 or 50 is a safer bet in a higher milage car. my car never gets tracked just daily driver.

What's the miles on yours ? Mines pretty low mileage.

I've already got the oil now so will give it a go and see what it's like ;)

103k mate but some of the others are lower milage than mine im just giving you my thoughts and experience with this oil

Im still new to imprezas myself and its all a learning curve

Been running silkolene pro s 10w50 since i've owned the scoob 3 years ago, it's now done 97k miles and engine is sweet as, hardly drinks the stuff, typically 0.5 litres between 7500 miles.

Scoobs like being warmed up and cooled down gently anyway, don't listen to gossip and hearsay too much just listen to your engine when the stuff is in.

i use 10w 60 fully just to really upset the apple chart lol and ive bene using it for a long time now im running 350bhp/340 fast road i always let my car warm up for 6-7 minutes before driving it and subaru tell you to do it in there hand book to, as your piston are horizontel and gravity will pull on them and the crank will be pulling them in another direction so you want some good oil pressure with some good oil temps lubing them up,

If worried about prolonged high revs (therefore oil getting very hot/thin), then a 10W-50 (a '60' hot weight isn't recommended) such as Silkolene Pro R should be able to comfortably handle road and trackday work.

Im using Millers 10W40 CFS oil at over 400bhp, my engine holds around 3bar oil pressure on idle at over 100 degrees, no issues at all.

I have this oil too (Zen supplied/serviced).