Splitpin

Nobody here has actually claimed that this is Subaru specific. It may be a phenomenon that affects other cars - but, thanks to an active online user community in which people share experiences, it may simply be that it's easier to spot a trend on an Impreza than it might be with, say, a Daewoo Expresso or (insert random car here).

Again nobody has said that not going the extra 10 yards is guaranteed to result in a blown engine. There are no doubt plenty of other Imprezas with big mileage that have never had anything other than a "normal" oil change. Although, seeing as you have an 02 STi, it's possibly worth pointing out that the crank in your engine oils better than the ones in the classic shape. Why do you think Subaru revised it?

Also, for those of you who come up with the "well you don't have to do this on other cars" argument (and I can eminently see why), the bottom line is that the EJ20 engine isn't "any other engine", it is what it is. This is frankly a bit silly, because anyone with half a brain knows that the engine is unique in its design - otherwise why do the spark plugs go in the sides, rather than the top, for example? The simple fact that it's a flat four has an implication for the width of the bearing shells that doesn't apply to an inline engine, for example.

The oil system is designed the way it is, the galleries are the volume they are, the main bearings are the size they are, the fuel pump looks the way it does. The ECU will allow the engine to reach a set rotation speed before initiating spark and fuel. All those (and many more) factors will combine to affect the way that oil pressure in the engine is developed during start-up.

It could be that something as subtle as changing the point at which the ECU switches on spark and fuel, and allowing the engine to turn an extra rev would fundamentally change the nature of this "issue". It could be that it is a lot of fuss about nothing and the "post oil change failures" are pure coincidence. Short of someone spending a lot of time and money researching the oil flow through the engine it's impossible to know for sure.

The bottom line with anyone who adopts the "you don't have to do this with other cars" line though, is to simply ask you to explain the repeating phenomenon of Subaru engines suffering bearing failure shortly after an oil change? The best tappets man further up could come up with is "you do it your way", which isn't exactly an answer.

I appreciate that engines fail at some point, and the law of simple averages will say that some will do so after an oil change, but are you suggesting that the frequency of threads like this is pure coincidence? Can you give us a coherent explanation for the chap whose engine was fine before the change, and then had knackered mains immediately afterwards (no filter or crank sensor mucking about involved)?

Why?

Why?

Yawn, this is starting to get a bit boring, but once again, just for the hard of hearing, nobody is saying that you are guaranteed to break your engine if you don't do the extra stuff.

What has been said, time and again, is that doing the extra stuff, as simple as it is, is worthwhile insurance. And as you've just acknowledged that you have in the past done both the filter prefill and spark disable, you seem to be on the one hand tutting about "****" oil change procedures while freely admitting to carrying them out yourself. Contradiction?

And, for the record, short of stripping an engine down after every oil change, you have no way of knowing for sure whether momentary contact has occurred.

With them it's tough, isn't it? Indeed one of the other issues that the "don't need to do this with Fords" brigade don't really address is that in most cases you simply can't do the same thing with other engine types. It just so happens that on the EJ the filter is vertical so can be pre-filled, while the crank sensor is easy to access and unplug.

Is it a cure for world peace? No, but it''s possible, it's a piece of pee to do, and unless you can come up with a better explanation for threads like this, seems to be worth 20 seconds of your life when you change the oil.

ariser

Can you unplug the bf2 fuse in the engine bay fuse box (ecu/fuel pump etc) instead of the crank sensor as mine is a pain to get to as the early classic i have has a lead going off somewhere in the centre of the engine where the plug is and not on the sensor itself like some i have seen.

JohnD

iTrader: (5)

No, I'm not contradicting myself. I did say "what some might consider" not "what I consider".

The Subaru engine is not unique - EG VW Beetle, Porsche.
I do aggree that it's getting a tad boring, though!

JohnD

Splitpin

Acknowledged - hence the question rather than a statement!

No, the EJ engine is unique. Other manufacturers do (and have done) horizontally opposed engines, yes. Hell, Subaru now make another 2.0 litre flat four engine (the diesel) that is a ground-up totally different design to the EJ, as well as the H6.

While all of these engines have a common design concept, each is unique in its combination of qualities, and each will have its peculiarities, advantages and disadvantages. It's for this reason that the "you don't need to do this on a Mazda" argument falls apart. You probably don't need to do it on a Tribeca, or a Legacy TDi - but there's plenty of anecdotal evidence to suggest that doing it on an Impreza is worthwhile.

It costs nothing bar a few seconds and might save you a lot of money, time and hassle. That's pretty much the bottom line.

Anyway, Tom, any news?