Subaru Forester Owners Forum banner

1 - 11 of 11 Posts

·
Registered
2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
Joined
·
106 Posts
Discussion Starter #1
I will be changing the oil soon on a 2003 Forester 2.5X. It has 142,000 miles on it and I notice that piston slap noise when I just start the engine and it's cold. As the engine warms up it seems to get quieter.

So my questions are what brand oil and weight are you guys running in a high mileage motor like this and also are you guys using any oil additives? Also is there anything under the car I need to peel back to access the engine oil plug and filter. I see a dust cover under the car, but I'm not sure if i need to peel it back for better access?
 

·
Registered
2004 XT 5 MT
Joined
·
1,092 Posts
I use the castrol 0w40 full Synthetic available from Wally World for cheap. It’s got a super low pour point so it flows when cold, but also is a 40 weight so it doesn’t shear down past a 30 weight.

It’s a great oil and a real sleeper because it’s a true Full Synthetic unlike some other full synthetics.
 

·
Registered
2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
Joined
·
106 Posts
Discussion Starter #3
What about additives. Do you use any Oil Additives?

I use the castrol 0w40 full Synthetic available from Wally World for cheap. It’s got a super low pour point so it flows when cold, but also is a 40 weight so it doesn’t shear down past a 30 weight.

It’s a great oil and a real sleeper because it’s a true Full Synthetic unlike some other full synthetics.
 

·
Registered
2004 XT 5 MT
Joined
·
1,092 Posts
No I don’t use additives and in my experince they tend to be snake oil. Try the thicker oil I bet it helps. I run that oil in all my vehicles that spec 5w30. I run it in my 2012 Subaru Outback, 2018 f150 ecoboost and 2015 t150 ecoboost Transit Van.

It’s 25 bucks at Wally World you cant go wrong.
 

·
Premium Member
2019 Crosstrek 2018 XT
Joined
·
14,213 Posts
Forget additives. Try a 40 wt oil. You din't need 0W40. Any 5W-40 is fine.
Try a can of seafoam in the gas tank. Do it a couple times in a row.
 

·
Registered
1999 Forester S
Joined
·
457 Posts
We use enough oil that a synthetic isn't really worth the extra cost. We're in western Washington, so we're in the snow enough, but not in arctic temps and occasionally see 100 degrees F in the summer. I run 10w-30 all year around with zero issues.

If the cold-start piston slap is getting worse, it may be time to replace the PCV system (valve, hoses, plastic tee, etc.) Ours was gunked up really good, with about 70% of the diameter of the hoses blocked by oil coke. Replacing these parts and the oil separator plate one the back of the block (when the engine was out getting new HGs) made a BIG difference. Went from sounding like a diesel on cold mornings to sounding just slightly knocky, and clears up a lot faster too.
 

·
Registered
1999 "L" - 231,000 mi. AT
Joined
·
715 Posts
I notice that piston slap noise when I just start the engine and it's cold. As the engine warms up it seems to get quieter.

So my questions are what brand oil and weight are you guys running in a high mileage motor like this
my '99 with 225,000 stills sees 5w-30 dinosaur oil of whatever brand, often Castrol. On startup noise; when I start it first time of the day I make sure to idle it for 3+ minutes before driving off. Makes a difference in the noises and the A/T rpm shift point for my car.
 

·
Registered
2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
Joined
·
106 Posts
Discussion Starter #8
Do you use synthetic or something else?

And I forgot to ask what oil filter you guys like for these high mileage Subarus?

my '99 with 225,000 stills sees 5w-30 dinosaur oil of whatever brand, often Castrol. On startup noise; when I start it first time of the day I make sure to idle it for 3+ minutes before driving off. Makes a difference in the noises and the A/T rpm shift point for my car.
 

·
Registered
1999 "L" - 231,000 mi. AT
Joined
·
715 Posts
On oil filters, I've used many brands and can't tell a difference, so I'm with soobcrazy^^^; get what's on sale.

Do you use synthetic or something else?
My answer was "my '99 with 225,000 stills sees 5w-30 dinosaur oil of whatever brand, often Castrol," which is to say conventional non-synthetic oil. I do change oil often.
 

·
Registered
1999 Forester S
Joined
·
457 Posts
On oil filters, I've used many brands and can't tell a difference, so I'm with soobcrazy^^^; get what's on sale.
As long as the filter meets factory specs. Many, if not most, aftermarket filters don't meet factory specs, anti-drainback valve, shape of the O-ring, etc. Just depends on your comfort level and risk aversion.
 
1 - 11 of 11 Posts
Top