tomo2323

Hi guys, bit of a stupid/amateur mistake in my Bugeye but here goes....

Had my oil change done in December by Subaru main dealer to keep up the FSH, its now Feb and I have noticed the oil is on the low mark which is concerning. I only checked it two weeks ago and I swear it was higher than that!

Anyway, I topped up with some Shell Fully Synthetic 5/40w in a panic that I had on the shelf.... came in and looked at the invoice and saw they used 5/30w, looked in the handbook and saw it should be 5/30w. So now I have just under 0.5litres of 5/40 mixed in with my 5/30.

I really didn't want to change the oil and filter as its so new but I am scared of dreaded big end failure and don't want to do damage by mixing oils.

Should I drain and refill with new filter and 5/30 or just leave it and carry on topping up with new 5/30w?

Will I have done much damage letting it get on the low mark?

p.s should it have used nearly half a lite of oil in 2.5 months?!?! Never owned a Impreza before so not too sure on oil consumption

Cheers

360ste

iTrader: (1)

That won't be an issue as a top up any oil is better than none. I am sure a /30 is too thin unless in very cold area's of the world. I have always used either a 10/50 or a 10/60.
http://www.opieoils.co.uk/ go onto this site to find the recommended oil for your car.

Re-reading your post as you have added a slightly thicker spec oil it will have no detremental effect. My bug sti uses next to nothing on 107k miles original internals, don't think I have topped it up since last oil and filter change. You could do with recording how much you add and mileage covered to get an idea of usage.

tomo2323

Thanks for that quick reply... I only assumed 5/30 as the main dealer fitted it and it is the main recommendation in the book and online stores. I will check out that site though as I have heard people using 10/50. Perhaps it would prolong the life of the engine using a thicker oil.?

360ste

iTrader: (1)

The thing is the lower the number the thinner the oil. But going to thick can be as bad as the oil won't flow aswell.
Always ask if you are unsure, okay you will get some **** taking if tpo that person you asked a daft question, but you will also get people giving you good answers. You will learn who to ignore, I will always answer honestly and to the best of my knowledge. I have had my bug STi since 2002 modded to 440 bhp and have serviced, repaired and modified it myself if not beyond my capabilities or needed spec tools.

F1 CJE UK

iTrader: (8)

Opie are great on price and advice.

tomo2323

They also seem to recommend 5/30w .....bit of a worry when there is a lot on the forums saying 10/40 - 10/60 :/

I do a lot of short journeys.... under 30 mins. I do drive it hard sometimes but never track days and only when warmed up/cooled down properly. I do continually worry about big end failure so I want to prolong the life of my engine as the mileage is getting high at 75k!

ianbott

The higher number is not the thickness of the oil it is the operating boundaries of the oil. Google it and it will become clear, using a 60w oil on a road car is silly as the oil will never get to its correct operating temps and if it doesn't then it isn't protecting.
Oil has a range at which it offers the best protection, please don't be fooled by thinking the higher the number the better.
On a standard car use the standard oil Subaru recommended but as already said using a small amount of the 10w40 will have no effect on the engine providing it meets the correct specs ie A3 B3 or whatever the handbook states.

tomo2323

Thanks for that Ian, that makes sense

I looked in the handbook and it states SL,SJ or SH classifications. At a recommended 5/30w.

What confuses me is a product like this high end Shell Helix does not list that it meets the Subaru API classification

http://www.opieoils.co.uk/p-68973-sh...ngine-oil.aspx


However the cheaper Helix oil says it complies to API SJ .

http://www.opieoils.co.uk/p-69317-sh...-af-5w-30.aspx


This confuses me a lot. So basically the expensive Shell oil I topped up with doesn't meet the standard but the cheaper one does? Doesn't make sense to me.

I think I will just drain the sump and hope I haven't done damage, would it be ok to re use the oil filter as its 2 months old?

oilman

iTrader: (9)

Topping up with the 5w-40 will be just fine, all engine oils mix without issue.

What year is your Impreza? And is it modified at all?

Cheers

Guy

tomo2323

52 Plate mate, and totally standard (turbo).

Thanks. I have also noticed that all the Shell oils comply with ACEA standards in the handbook... didn't notice those :/

oilman

iTrader: (9)

Hi

I would use a 5w-40 synthetic and you will find those through the link below.

http://www.opieoils.co.uk/c-656-5w-40.aspx

Out of those, the best ones are the Fuchs/Silkolene Pro S, Millers CFS/CFS NT, Motul 300V, Redline and Gulf Competition. The Motul 8100 X-Cess, Millers XFS, Fuchs GT1 XTL/Supersyn, Shell Helix and Mobil Super 3000 are good, cheaper alternatives.

Cheers

Tim