With my old standard WRX engine it didn't hardly use any oil at all. I've noticed with my new build (CDB EJ20, forged Wiseco rods and Eagle pistons) I'm emptying my oil catch tank a lot more than I used to and needing to top up the oil a little every couple of weeks - it's done 2000 miles since the build and has probably used 3/4 to a litre of oil.

Is this normal? I'm guessing that with a lot of cold starts (and the resulting rattle until it warms up properly) there's a bit more oil blow-by than on a normal engine - is this the cause of the greater oil useage? BTW it's my crankcase catch tank that's collecting a lot, the cam covers tank is pretty dry.

Cheers!

 

Bigarf had a catch can on his catch can on his Chy built 2.5.... over 70 miles it spat about a coke can's worth of oil into No.2. catch can being used properly !

As far as I understand it, the forged pistons will allow more oil past whilst cold, and as a result some wil be burnt, some evacuated into the catch-can.

I.M.H.O.

dunx

 

What clearance are you running on your pistons?

But in general forged engines do tend to use a little more oil.

 

I dont see why they should, after all most sti's have forged pistons as std.

Saying that, 1l per 1000 miles isnt out the ordinary for a turbo engine (as stated in some owners manuals)......

 

My STI has never needed an oil top up, and that equates to 3 litres lost per oil change !

Ekk !

dunx

 

LOL

 

Yes, Sti's have forged HF pistons from the factory but the piston to bore clearance is 0.001", much tighter than your average 0.003"+ from the major aftermarket piston manufacturers.
A "built" forged engine will use a little more oil than a standard engine mostly due to the larger clearances/ring gaps.
The pursuit of performance is always a compromise but as long as you have a big grin on your face after nailing your favorite bit of tarmac - thats what its all about


Mick

 

my 2.5 uses a fair amount of oil but its due to the large piston clearance i think it is 0.003" for my wiseco pistons but its worth it for the grin factor.

 

Well that all puts my mind at rest. The clearances were what Wiseco recommended, I can't remember off the top of my head but it was at the tight end of usual forged aftermarket pistons' ring clearances - 0.035mm and 0.050mm 'rings' a bell (excuse the pun) for the 1st and 2nd rings?

 

I do beleive Wiseco recommends piston to bore clearance of 0.0025" so anything bigger than that is bound to use more oil than intended.

I use approx 1/2 litre every thousand miles with my 2.5 wiseco's and have done so without issue for around 10000 miles, having said that though my catchcans are always dry.

 

Oil lost to the catch can is not oil that's burned.

Nick,

I think the biggest thing with your current change in oil loss, is the increase in performance, which does a number of things, increased power puts more heat into the oil, increased RPM creates more oil vapour, increased airflow (which you now have) creates more blow by on a %age basis and increased acceleration increases the oil loss through the crankcase breather due to it's location (without preventative measures a 550hp car can lose 0.5L on a hard launch through that back breather.

In short it's nothing to worry about, but installing a catch can with a return to the sump will alleviate the problem.

Paul

 

Jesus..... that's some oil!!

I have never needed to empty my catch once in 10k miles on my built 2.5, and that certainly has been "used properly" (and no it does not return to the sump lol).

 

I recently did about 500miles and checked the car and it had used about 1/2ltr

 

Shaun, that was about 10 miles before it went "bang" and the AA took four hours to find us in Muker up past Tan Hill Pub.

It went back and was stripped and re-built and then after running in, the bottom end started knocking on the rollers as it was being mapped !

Ekk !

dunx

 

I'll try and do the return to sump idea then once I get back from the 'Ring, and in the meantime just keep emptying it once a week! Cheers!

 

My 2.5 uses about half a litre every 1000 miles, I check the level every week just in case. I don't have a catch can, should I be using one?

 

Ahhhh... that would explain it then!

 

Absolutely makes sure you check the catch can there - you do not want to be dropping oil on the track and causing accidents for which you will be held responsible under law.

 

I've fitted a catch can due to breather delete silicon intake pipe, and all I've seen so far is a bit vapour.... std STI engine still hanging on.

dunx

 

my car being the legacy rs has forged pistons and rods as standard and i havent used any oil in the last 3 months always dead on the mark every morning.

 

Do you drive it or just check the oil every morning

 

ive done almost 1,000 miles since the last oil change and hasnt used a drop, just a thought what oil do you use i use 10/40 semi synth does the fully synth burn up quicker.

 

Although I do applaud legacytt's conscientiousness/paranoia [delete as applicable]

 

hey be gentle this is my first subaru and with them being renowned for big ends going due to lack of oil and leaks then im going to check whenever i use it rather than find out later.

 

I'm kidding.

No, absolutely - after all, low oil level can easily be prevented, so absolutely sound thinking.

Just think how gutted you'd be if a big-end went because you didn't check the oil level and it happened to be low (this happened to me with my previous beloved Integrale Evo I)