ariser

Hi i have a 1993 wrx and currently use 10/40 semi for oil changes as it says in my book and on autodata but would like to know if 15/50 is better for the car as its hitting around 90k miles on the clock. The engine is tappety from time to time only when hot and the previous owner used mobil one 15/50 i think as there was an empty bottle in the boot. I dont do loads of miles and change my oil and filter every 2 months as i work in the trade. What sort of benefits would using a fully sythetic 15/50 make over the 10/40 semi? Would the 50 make the engine less tappety at higher temps? I have light mods including a chip, full decat and panel filter. Car is probably around 275-280 ish bhp.

Cheers all

TonyBurns

iTrader: (3)

At those miles your pretty much wasting money on the 15w50, but it will quieten your engine down, though I always thought that it should be tapperty when cold and not hot as the oil has better circulation by then, and its not worth changing a fully synth oil every 2 months with low miles, every 6 months is more than enough.
Still I would be wondering if its tapperty at temp or if its something else?

Tony

Sp33xX

just a personal thing i wouldnt use a 15w grade oil in mine. 10w is ment to be best according to subaru after that its a mine field wether you go for 40 50 60 basicly the hotter your car gets the higher the grade you want. semi or full synth both good fully is better and longe lasting have fun.

TonyBurns

iTrader: (3)

No a 15w is good its the 10w60 you have to watch out for, that last rating is the hot rating and 60 is too think really

Tony

Sp33xX

lol here we go again. i said its a personal opinion i know the first number is the cold value. saying that! 10w is recommended by Subaru but in theory the thinner oil is when cold he easier it is and the faster it gets to the components that's good. so 15 would be thicker and get there slower i would say bad. scoobys are meant to like a slightly thicker oil again theory so i go in the range i like not 0w not 5w but the manufacturer suggested 10w. just what i do

ariser

I guess ill stick with my 10/40 semi then . I assumed its a tpappety noise but could be injectors but not causing any running issues at all. I guess i could go down the 6 month oil change route and use a 15/50 synth.

oilman

iTrader: (9)

What 10w-40 semi is it you are using?

Cheers

Guy

ariser

Im using the gm 10w/40 semi synthetic oil we use in the garage here where i work its acea a3,b3,b4. api sl/cf specification.

oilman

iTrader: (9)

That will be ok, next time try a decent synthetic and give it a good hard drive and see if it stops the noise.

Cheers

Guy

ariser

do they do a 10/40 synthetic I've got lots of good quality 5w/40 at work but always worried it would be a bit thin?

TonyBurns

iTrader: (3)

5w40 was the rating that mobil did for subaru as a fully synthetic oil, if you want a 10w40 fully synthetic then Motul do one but the 5w40 is fine

Tony

ariser

I'm just paranoid about putting it in a 1993 car did synthetic exist then lol

TonyBurns

iTrader: (3)

Synthetic has been around longer than me, and thats quite a while

Tony

ariser

lol :P

Wagon Gaz

iTrader: (18)

Ran all my Scoobs, classic and newage on 5w 40 full synthetic with no probs

oilman

iTrader: (9)

It should be fine but we've FS 10w-40's on the shelf too.

10w-40, 10w-40 oil, 10w40, 10w/40 Oil Products

Cheers

ariser

And of course I'm a bit dense thinking 5w/40 is too thin as the 40 is the hot part.

oilman

iTrader: (9)

Indeed the 40 at 100degC is about 40 times thinner than the 5w part at 10degC!

Cheers
Guy