2008 2.5i Piston Slap?

I've bought a 2008 2.5i this summer and soon after hitting cold weather here in Toronto, the car started making this crazy slapping/ticking/knocking like noise when cold.

I did a lot of search and it seems like piston slap is notorious for Subaru's, but not in recent year models.

Mine is very loud in cold acceleration, but not at idle. As soon as I start moving the noise starts, but after about 10 minutes of driving (completely warmed up), it goes away completely. The noise is so loud I wouldn't have bought this car if I knew, and it's so embarrassing to my friends sitting beside me because I raved about how great the car was...

During the summer, I really enjoyed this car because it did not make any noises but it's really starting to bother me now.

 

I just did my 96,000km service at a reputable garage and the mechanic said it's normal when cold, but I've never owned a car that makes this garbage noise when cold.

Now, is the piston slap problem still prominent in recent year models? Luckily I have extended warranty until 160k, should I bring it to the dealer and ask to fix it under warranty? They can't possibly say it's normal....but I'm afraid they will. What does it take to fix it?

Does it sound like this: [ame=http://www.youtube.com/watch?v=p98AqJhH9Qs&feature=related]YouTube - Subaru Piston Slap[/ame]

I saw this video, and number of others, and yes, it does sound like that. Except mine is not as bad at idle, but as soon as I start to move that's when I hear the noticeable and annoying tap tap tap tap tap.....

Try making a video of it, it may help to diagnose it properly.

Sounds more like top end rattle from the hydraulic tappets (valve lifters). Try using a thicker oil.

I had a car start to do that on me around 150k. Half qt of Lucas oil stabilizer with an oil change helped tremendously!

Right now I've changed oil about 2 months ago with Pennzoil 5W30 dino, the yellow bottle, and according to the maintenance history this car has always been on 5W30 (factory recommendation), various brands of oil. I've never tried thicker oil so I'm kind of reluctant to try but I'll definitely consider it.

I used to use Lucas oil stabilizer on my old Civic but I don't know if it really does anything...if it did help you though, maybe I'll try that next time too.

But even with regular 5W30 I think it's supposed to be ok, isn't it?

I'll try to post the video next time I do a cold start.

Switch to 5w40 or for your climate 10W40 to help with the cold. My 08 did the same thing around 5K miles I switched to Rotell 5w40 and the chatter went away

That sound is normal for boxer engines when in cold climates. If the noise didnt go away when warm then I would worry. I run 10w-30 in the summer and 5w-30 in the winter (wisconsin winter) with no problems. The sound wont just go away its just the way the motors are built.

That's what my mechanic said and number of other people as well.

Some people managed to get their pistons replaced under warranty but I guess I gotta be lucky to get that. (mine's still under warranty).

I think I'll bring it to the dealer anyway to see what they say. Just leaving the car there overnight to do a cold start next morning isn't fun...

 

For the time being I think I'm going to try Lucas because it thickens the oil and I think it might help fill the gap where the noise is coming from.

Maybe try rotella 5w40 t6 on your next change. I just got my 06 legacy, but I used it on recommendation from members here and I can already tell the engine seems quieter than whatever the previous owner used.

From what I understand, piston slap does not exist on modern Subaru engines any longer because the newer pistons have longer piston skirts so it is impossible for them to slap. What you are hearing is most likely top end valve or lifter noise. Thicker oil and/or a warm up makes this go away.

Also i read a post on NASIOC that 5w40 was THICKER than 10w40 but I thought the "40" is SAE grade and the 5/10w was the cold starting grade. Two 40 grade weights perform the same at operating temp.

Ah, interesting. So it might not be piston slap. Can the dealer fix the valve or lifter noise then?

Honestly I've never used oils other than 5W30 in my life so I'm reluctant to try it but I see other people use it all the time. What would I be compromising by using 5W40? I guess that means synthetic only...

Also I thought lower the prefix better crank in the winter so a lot of people here use 0W40. Would using a heavier oil lose MPG on my car, or create any other issues?

Not sure if you check your oil but it does sound like the lifter are knocking or making noise, on my old E-GT it would do this when the oil was thin or cold and I would have to add oil and it would calm down with more oil. check oil like stated and change it make it thicker.

Ah, interesting. So it might not be piston slap. Can the dealer fix the valve or lifter noise then?

 

From the first time I test drove my car, till today, I've had noisy valves, and I've brought it to a lot of people, and everyone says that it is normal. comparing it to other cars, it is a lot noisier, but it seems that it is fine.

 

I'd say just live with it, it seems like subaurus (oratleast the 2.5i) are noisy cars.

 

Edit: just saw you live in toronto, I live in mississauga and commute to toronto everyday for school, so if you wanted to hear mine/me listen to yours just lemme know and we can meet up or go to a meet.

Well it seems like I'm just panicking with my first winter with my first Subie, but really, I definitely thought there was something wrong with the car when I heard that noise. I've owned/driven many cars and none of them made that kind of noise in cold.

Anyway, it seems like the majority is leaning towards thicker oil theory (which I think makes sense at this point), so I'm going to go ahead and put in 5W40 on my next oil change in about a month. Really interested to see the result.

 

sulk - thanks for the suggestion. I'll let you know if I still have doubts, after trying thicker oil. I live in Markham and commute to downtown everyday for work.

 

Thanks everyone, I really appreciate all your help. I hope this will be helpful for other first time Subie owners too!

Meanwhile, feel free to post up more ideas. I'll post a video when the weather gets colder...it was cold last week then it got warmer again, so only mild noise.

The H2.5 engine is anything but "refined" sounding. Several of my friends and relatives actually have said they love the sound of the Subaru engines. However they are dissappointed that my 2006 2.5i no longer makes the characteristic chatter of old Subarus. Exhaust changes I believe put an end to this if I am correct?

 

Almost all of my cars have made more noise when it is cold and it gets REAL cold here in Iowa so any oil is stressed to its limits. Just drive it easy for a few minutes until the oil can circulate and warm up. Don't do like the old timers and start your car and let it idle for 15 minutes which only wastes fuel. Your car will warm up faster if you just get in a start driving it, obviously no WOT until it warms up a little.

I do actually love the sound of Subaru engine, except the taptaptap when cold!

 

For those who recommended 5W40 oil, I'm trying to decide between 10W30 and 5W40, and I thought it made more sense to go with 10W30 because the noise is only around when cold. Is 5W40 generally thicker, or only thicker when warm? If 5W40 has got the same viscosity as 5W30 when cold, there's no point. Thoughts?

 

Also 10W30 means I can stay dino...although I don't mind switching to synthetic.

Castrol Syntec is on sale at CDN Tire so I might stock up.

IMHO there is no reason to switch to a 10W....ever. There may be some high performance cars that need 10W50 or some other heavier oil but they are the exception. You want oil to flow to the engine at cold start as quickly as possible, why would you want to slow that down by going thicker? Most engine wear happens at startup. If anything 10W will make the cold valve noise WORSE because the oil will take longer to reach all the parts of the engine. I also would not go to a 40W unless you are having consumption issues or the valve noise happens even when the engine is hot.

Hmm...now I've got a mixed opinion here.

Like I said earlier I was reluctant to change the oil weight but I'm willing to 'try' and see if it helps the noise because number of people here said it did for them.

I don't burn any oil and it's properly topped up. Would it hurt to try 5W40, and if it doesn't help I can come back to 5W30? I want to at least try something to eliminate the noise.

When the mileage on an engine mounts up then the specs for that engine change due to wear and tear. I ran a high mileage Merc 500 v8 which when I bought it had tappet noise for a minute and a half after start up . Spec for this was 10w -40. Only thing that cured the noise was running on 15w- 50 and it ran sweet as a nut for all the time I had it. With this oil then drain off from the camshafts on engine switch off was less than the thinner oil.

It won't hurt to try a 40 oil and you can switch back whenever you want.