Having recently bought a fantastic STi V in cool grey I've become increasingly paranoid about blowing the engine.
Sorry to say I know a few of you members have suffered this - I don't want it happening to me so reckon I should post the sound advice received from Bob Rawle of BR Developments !

Has any STi owner NOT had an engine explode ??!!

"The STi V5 (or V6 which is virtualy the same car) being designed for the Japanese market can both suffer when used in the UK. The main reason these engines fail are :

1) detonation due to use of incorrect fuel and

2)incorrect or "inferior" oil and poor servicing procedure. Most failures are big end bearing related with some snapping a conrod in the process.

So what precautions to take given the car remains standard ... I assume yours is ie original exhaust and induction set ups ?

1. Always keep the car off boost when cold, the oil temperature must be at least 80 deg C before you boost the car, don't be misled by the coolant temp guage, you need to have driven at least 8 miles before the oil is at 80.

2. Letting it idle for a couple of mins before switch off is ok but only really necessary if, for example, you have been driving on the motorway at highish speeds and oil temp is higher than usual, you shouldn't then exit motorway, stop and switch straight off. If your journey involves normal roads with some traffic before and after motorway then all would be ok in any case.

3. Fuel ... sorry to say but 97 ron is not good enough, you need to at 100 ron (Japan is 102). The way to do this is to add Octane booster to your fuel. Suggest you star using 2mls per litre of 97 ron of NF booster, this will take it up to around that level. Be aware also that fuel quality varies greatly, I would stick to Esso, BP or Shell (Optimax) but defo avoid Texaco and never use Supermarket fuel even if it is 97 ron.

4. I would strongly recommend using Motul M300V Competition 15w-50, when I changed over I gained a bar of oil pressure at idle straight off, viscocity index is much much better. This can be bought from Demon Tweeks or ScoobyMania.

5. Oil Filter ... insist on the genuine Subaru part being used, some dealers use alternatives, so ask them to stick to the OEM
part. Its very high quality.

6. Oil change procedure ... basically problems can arise when the filter is not pre-filled with oil before fitting to the engine, be aware that if you fill a filter, let it stand for 10mins you will be able to put in the same amount again, it needs topping up until it stops absorbing oil which can take 20mins or so. I always remove the connector from the crank position sensor and then crank the engine a few times, this starts the pump moving the oil around, then I refit connector to start engine. This is not essential but the filter filling is.

7. Never hold the car at high revs and high load for any length of time, in Japan the car is speed limited and so this would never happen in 4th and 5th, in the UK we do it and the extra heat can cause a hot spot or pick up in the bearing, later on, say as you slow down on a motorway slip road, the bearing loading changes and the bearing picks up and thats that. The red line and rev limiter are to be avoided.

8. Never carry out any mods to the car without getting it checked for correct fueling and det, its easy to fit an induction kit but that can cause lean running and det plus increased oil temps.

Having said all that there is still no absolute guarentee but if you pay attantion to the above you will be in best shape possible. The cars are great, the real problem is that they are in UK not Japan, so sort out fuel and oil quality, some TLC re revs etc and you ought to be ok. I've remapped loads and loads and I love them, they tune really well but just need the TLC to go with it."

He sure know his stuff !!

 

Well mine has not exploded yet - and it has spent a lot of time between 5-8,000 rpm om track! It has also done 52,000 roads miles and been tuned to within an inch of its life!

Trout

PS Does use Motul 15/50 oil tho!

 

Ah but you've been running it on only 3 cylinders to reduce the wear ho ho ho

 

Maybe they are rock solid and never blow, but if they do they're driven by people with no respect

 

Don't hit the rev limiter too often. Imagine the stresses that occurs (engine braking, no fuel, hi revs, hi temp)..

 

**** it - drive it how you want to - if it blows build a faster/strongr engine. If you people are worried about costs why don't you go out and buy a ford fiesta

 

Agrees about hitting the rev limiter - I like the way Merv always uses it to see how high my car can rev....8,500

Have always treated car with respect, lots of oil changes, but it has been driven hard and tuned hard. Currently running 1.5bar with 1.65bar overboost.

It is still running fine. Maybe it is time to test it to destruction now I have all four cylinders working now!

Trout

 

I know that John Felstead has had lots of happy miles out of his STi5 type RA V-Ltd including track driving, but he also runs his car on optimax plus octane booster so keeps the octane rating high enough for its ecu.
Me, i just run mine on optimax but then again its a uk car

Tony

 

Guys, another point that should be raised is that oil change intervals recommneded by Subaru Japan to all STI's is 2500 miles with fully synthetic. I really dont know how Subaru UK recommend every 7500miles even with the P1 which engine wise is identical to the STI5.

 

STI4: 348BHP, 72K miles, still going strong.
However, I've had PE map my car for 95RON (although I always run 97 anyway), I run an oil cooler and water injection just in case.
Even if it did go bang I would feel 72K miles with that sort of tune, was a pretty good run for the money.
Just had the 75K service and if anything the thing is running quicker and better than ever. Mind you it does have a little bit of piston slap when cold, but I've lived with it so long I just treat her gently until shes warm.

 

Would these rules apply to my STi4, or is the problem only on 5 and 6's. Also where do you get this NF octane booster?

Thanks

Daz.