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Old 12-19-2003, 04:47 AM   #1
Scooby Newbie
Member#: 50874
Join Date: Dec 2003
Location: BC Canada
98 Outback Ltd

Default '98 OB piston slap - 2.5 AT

I had a service done recently by an independent mechanic who used to work for Subaru ("master mechanic") and told me that I should be using different oil. Specifically, he said, a formulation of 15W40, is the best way to deal with the chronic piston slap...hmmm... So I'm thinking: that's the same oil specs for my Ford Diesel F250 pickup. Seems mighty odd to me. Anybody else heard of this 'solution' for Subaru piston slap? One more thing: he says that the timing belt should be changed, despite my low mileage, because they "just go kaput, and fry the motor." I know what timing belts failure can do, but I thought that the problem with these '98s was not so common, and that it involved the tensioner, with some warnings first.... Suggestions? (I bought this car new; it's got relatively easy miles on it.) thanks
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Old 12-19-2003, 06:55 PM   #2
Scooby Newbie
Member#: 50148
Join Date: Dec 2003
Chapter/Region: NESIC
Location: ellswroth, me
2004 sti

Post ?

i agree with you about the oil. it sounds very odd. i work at a subaru dealer and i have never herd of that oil combo before. as for the t-belt i bet hes trying to make another buck of of you.
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Old 01-07-2004, 07:30 PM   #3
Mike Rockefeller
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Member#: 52154
Join Date: Jan 2004
Location: Upstate NY
1998 Outback Wagon


Consider changing the timing belt tensioner. When it is weakened , the tensioner will knock up against the engine. It leaves a dent in the tensioner around the little piston. A new tensioner cost me $140 us, and replace the timing belt too . ?? Does the backside of the timing belt look torn up ? If so , take off the belt guide over the center crank and throw it away. Per Subaru dealer mechanic.
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Old 01-15-2004, 06:43 AM   #4
Rally Medic
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Join Date: Oct 2002
Chapter/Region: BAIC
Location: Gravel Crew HQ Medic
1998 Outback Sport
Dirty with some mud flaps


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Old 01-27-2004, 12:30 AM   #5
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Member#: 11148
Join Date: Oct 2001
Location: Kamloops, BC, Canada
Thumbs up

Why not try the 15W40? Heavier oil, and if you are in lotusland, you don't have to worry about the oil getting too thick in the cold.
We have a '98 OB also, and have the same piston slap issue. I'm sure you know about the whole story about the "need to warm up" and how "tolerances improve when warm". My wife is chronically running late, and she would just start the car and give'er - not so good. So I got her a remote starter, and now she always starts it early - she gets a warm car, and no piston slap.

But why not try? It's not going to hurt


PS I run 15w40 in my Datsun roadster all the time - it has issues with timing chain tensioners, and the heavier oil stays in the tensioners a little bit better that 10w30
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Old 01-27-2004, 02:22 PM   #6
1 Lucky Texan
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06 WRX Sportwagon
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