scoobyc

iTrader: (2)

Im going to do a service on my subaru tomorrow. Its got 64k on the clock and is a 98 sti v4 import.

I shall be buying everything from halfords unless thats really not a good choice.

What oil should i be putting in? Seems previous service used 10w40.

I have also heard many people chew their big end up after a service. What are the tricks of the trade to stop this from happening? Prefil the oil filter when putting it on. Will a halfords/bosh oil filter do? Can you get these stuff for this import from halfords?

Whats the sump size? Should i use some engine flush?

Is there a haynes or anything like that which can help answer all these questions?

I will be tracking the car next weekend for the first time.

scoobyc

iTrader: (2)

anyone?

joz8968

iTrader: (13)

Im going to do a service on my subaru tomorrow. Its got 64k on the clock and is a 98 sti v4 import.

I shall be buying everything from halfords unless thats really not a good choice.
Not really (see below).

What oil should i be putting in? Seems previous service used 10w40.
Fully synth 10W-40 is fine... preferably the 100% Ester types e.g. Silkolene, Millers, Motul, etc.

I have also heard many people chew their big end up after a service. What are the tricks of the trade to stop this from happening? Prefil the oil filter when putting it on?
Prefill! and fit the filter (lightly smear some oil with finger around rubber o-ring)... pour in oil via filler neck (see below)... disconnect the crank and cam sensors... preferably remove the spark plugs too!... Then turn engine over to prime the pump until oil light goes out. Can take a few turns.

Will a halfords/bosh oil filter do? Can you get these stuff for this import from halfords?
Stick with genuine Subaru OEM spec items.

Should i use some engine flush?
NO!!!

Whats the sump size?
Oil capacity is 4.5 litres INC. filter. Put in about 3 litres... Then, little by little gradually fill - keep checking dipstck - till level reaches the topmost 'full' hole in dipstick (and NOT the semi-circular notch in the side further up!).

scoobyc

iTrader: (2)

cool. you got an owners manual or something?

joz8968

iTrader: (13)

There are owners manuals but, from memory, they don't really tell you the procedure.

The above advice is the generally accepted oil-change practice for the Subaru flat-4 engine (and other engines in general).

scoobyc

iTrader: (2)

Why is removing the crank sensor important? I have read it may cause engine check light to come on. WIll this be the case with a 98 classic?

Im not doubting your advice, i just like to know exactly what im doing and why.

joz8968

iTrader: (13)

For some reason the flat-4 engine can be susceptible for a big end to pick up after an oil change, so the priming process needs all the help it can get with regard to keeping the cranking pressure as low as possible. Hence the disconnection of the crank (or cam?) sensor - one of them disconnected prevents the ECU from delivering the spark to the plugs. This obviously stops the engine from firing, thus removing the enormous pressures that would otherwise be delivered to the big ends, during the pump priming process - the only pressure present being that which the starter motor can muster (which is significantly less than a firing engine!).

To this end, it's beneficial that the spark plugs are also removed, as any compression in the cylinders will be alleviated by being forced out through the plug holes too, thus further giving the bottom end an easier time of things.

Basically you're doing everything that is reasonably possible to stop a big end from failing after an oil change.

scoobyc

iTrader: (2)

yeah ok makes sense.

Ive gone for some Mobile 1 Super S Very High Performance Semi-Synth 10w40

This stuff good enough?

joz8968

iTrader: (13)

10W-40 is fine.

I'd personally use a fully synth, but a semi will be fine so long as you're sensible and don't ridiculously abuse the engine everytime you go out in it. A fully stays in grade longer than a semi or a mineral i.e. the molecular structure can hold its integrity better/longer given the, literal, mashing it faces by the forces involved.

Change oil - and filter/sump washer - at least 6 months, or 6,000 miles, whichever comes sooner. If you feel you give her a bit of mauling, then I suggest 4.5mths/4,500mls, or even 3mths/3,000mls...

scoobyc

iTrader: (2)

I couldnt find any 10w40 full synth. Where you get yours from?

joz8968

iTrader: (13)

I get mine serviced at Zen Performance and they put in Millers CFS 10W-60 last time. The 'hot' 60 weight is probably a little too thick TBH (esp. at this time of year), so next change in Jan, I'll use 10W-40 too.

Where are you based? If there are any Subaru or Evo specialists near you, I'd get either Millers, Motul or Silkolene, in 10W-40, from them!

UPDATE: Guy at Opie Oils - Oil Recommendations Specialists | Find the right Engine Oil & Performance Products has emailed me to say the max 'hot' viscosity suited to the EJ20 engine is up to, and including, SAE50.

See here for a comprehensive explanation from Guy...

I get asked all the time "why do you advise against the use of 10w-60?".

Let's get one thing clear, I supply 10w-60 and recommend it where it is appropriate for the engine or the application but conversly I caution against it's misuse!

I have debated this many times on many car forums and I know there are some that do not agree with me however I have never had a reasonable technical explanation why 10w-60 is in fact suitable, it's certainly not mentioned in the handbooks of many modern highly tuned performance cars, with the exception of some Alfa Romeos for "spirited driving" whatever that is meant supposed mean.

Explaining this is diffucult so there may be questions but I'll try my best to explain it in plain English!

Lets look at what oil specs actually mean and particularly the higher number which is in fact the oils SAE number (the "w" number is in fact the cold crank viscosity and measured in a different way) The SAE number is measured by the oils viscosity at 100degC.

Your cars require according to the manufacturers specs, sae 30, 40 and in some cases sae 50.

To attain the relevent sae number the oil has to be at 100degC (no thinner than)

SAE 30 11cst approx
SAE 40 14cst approx
SAE 50 18cst approx

Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid.

As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC.

SAE 60 is in fact 24cst viscosity at 100degC!

This is 33% thicker than an sae 50, 70% thicker than an sae 40 and over 100% thicker than an sae 30!

So, what's the problem with this thickness?

Well, this is measured at 100degC and at lower temps (70-90degC) all oils are thicker than at 100degC so the problem is compounded to some extent.

The downsides of such a thick oil (when not specified) are as follows:

Additional friction, heat and wear.
A reduction of BHP at the wheels
Lower fuel consumption

The thicker the oil is the more friction and drag and the more power the engine needs to move it around the engine which inevitably translates to less at the wheels.

So, when do we spec a thicker oil?

Well, you will probably have seen us on occassions recommending a 10w-50 but only in these circumstances.

1. If the car is heavily modded and heat/oil temperatures are excessive.
2. If the car is used on track and heat/oil temperatures are excessive.
3. If it's required by the handbook.

Our criteria for this is based on oil temps as an sae 40 semi-synthetic can handle around 110degC for limited periods whereas a proper synthetic sae 40 can hande 120-130degC for prolonged periods due to its thermal stability.

Once you see more than say 120degC for prolonged periods an sae 50 is adviseable as it is 18cst at 100degC and still 11cst at 130degC! This is in fact the same as an sae 30 at 100degC.

More importantly at 90degC an sae 40 is 15cst, an sae 50 is 20cst and an sae 60 is 30cst!

In a worst case scenario with thick oils (when not required) is that you will experience air entrainment and cavitation inside the bearings at high RPM. Not clever stuff!

I know this is technical stuff but oil is a combination of science and engineering and few people know enough about it to make an informed choice. Just because your mates use it and have had no problems is not a good enough reason to use it, your engine would prefer and benefit from the correct oil.

Cheers

Guy

scoobyc

iTrader: (2)

Ok. So will my oil temp gauge be sufficient to dermine what temp the crucial oil in the big end for instance will be.

From that i should be ok with 10w40 semi-synth , however it would be best i went for full synth, as this car is gonna get some track use.

I dont expect to the pushing the car for a few months yet while i get used to it, so i will probably service next time with some decent oil.

Im based in Berkshire. Im not aware of any scooby specialist in this area.

joz8968

iTrader: (13)

Use a decent fully synth 10W-40, or 10W-50, IMHO, based on info above i.e. a proper synthetic sae 40 can hande 120-130degC for prolonged periods due to its thermal stability. This should be good for even the most ardent of trackday usage, so would appearr to bridge the gap nicely between all road speed loads and loads experienced on track.

While you've got an oil temp gauge, wait for the oil temp to get to at least 80 C before giving your car beans. And if it's on track, back off if/when it gets to 120+ C


EDIT: Also from Guy...

"John,

Thanks for the mail.

If you are giving it beans then I would look to use the ester based Silkolene Pro S 10w-50, ideal and well proven.

Regards,

Guy."


Can get the oil from here: Roger Clark Motorsport - RCM Product Detail

Oil filter too: Roger Clark Motorsport - RCM Product Detail

ColiNThESTI

excellent v helpful thread as i also have a 98 JDM just to hijack the thread anyone recommend a good scooby specialist in Sussex as ill not be doing my own Oil change because i don't have a mechanical bone in my body

joz8968

iTrader: (13)

Polar Performance's Scott T is based in Sussex, I think. PM him (using his ident as it appears in bold) - he'll probably know of some Subaru specialists down that way.

ColiNThESTI

many thanks

scoobyc

iTrader: (2)

yes bloody good info mate. This should be a sticky!!!!