Mobil 1 EP 10w-40, 5100 mi, 04 Subaru WRX

Status
Not open for further replies.
Joined
Apr 25, 2004
Messages
331
Location
San Jose, CA
My second UOA. Car is a 2004 Subaru WRX with Cobb Stage 1 ECU mod increasing HP from 227 to ~255.

* Daily highway commute of about 60 mi round trip.
* Second run with Mobil 1 EP 10w-40. However, this oil has been discontinued. I probably have enough for another oil change, but will need to move to another oil later (Gold GC?)

Reason for this UOA is that the car uses a tiny bit of coolant (~half cup). Wondered whether it just evaporated or it actually leaked. Blackstone said no sign of coolant, and they tested for postassium and sodium as indicators.

Overall all wear materials trended down except copper. So car is doing fine.

Even better is lower fuel dilution and insolubles, which are the least bright spots for Subaru turbo engines.

Flash pt and viscosity stayed higher also so I think the 10w-40 EP has done better in the car than the T&SUV 5w-40. Too bad that it has been discontinued. M1 EP 10w-30 is too thin and 15w-50 is too thick for me. So I guess I will try the Gold GC once I have used up the EP 10w-40.

Any comments? Especially on the coolant issue? It seems that it just evaporated a bit to me. Thanks!

code:



Equipment Make: 2004 Subaru WRX (5MT Wagon)

Engine: 2.0L Turbo (EJ205)



Mi: 5,099 5,100

Mi on Car: 15,162 30,091

Sample Start: 09/24/04

Sample Date: 12/28/04 02/21/06

Brand: M1 T&SUV M1 EP

Viscosity: 5W-40 10W-40

Filter: Stock Stock

Make-Up (qt): 1/2 1/2



Aluminum 4 3

Chromium 1 0

Iron 6 6

Copper 5 7

Lead 1 1

Tin 0 0

Molybdenum 8 65

Nickel 1 1

Manganese 0 0

Silver 0 0

Titanium 0 0

Potassium 0 0

Boron 31 137

Silicon 11 7

Sodium 2 5

Calcium 2247 2500

Magnesium 377 10

Phosphorus 974 692

Zn 1139 797

Barium 0 0



SUS@210 68.9 71.7

cST 12.7

Flashpoint 365 385

Fuel % 0.5
Antifreeze % 0.0 0.0

Water % 0.0 0.0

Insolubles % 0.5 0.3

TBN 4.3 n/a


 
Check your coolant expansion tank cap. If it doesn't hold pressure you may be losing coolant there unnoticed. Also check the coolant expansion tank for cracks, especially around the hose barbs. Check all coolant hoses and coolant lines for signs of moisture and dried coolant deposits. You could also add a fluorescent dye to the coolant and find the leak with a UV light.
 
Just keep checking for leakage underneath the car periodically.

Great UOA. I was going to suggest you give the 10W-30 Mobil 1 a try. But the GC is a better idea. With the lead numbers the way they are. You can afford to try a 30 wt.
 
I had an early leak in a 2005 Forester turbo. It would leak maybe 100 ml in a short time, then stop. Dealer had it twice, said there was no leak. I thought the filler tank by the turbo had a leaky cap but dealer said no way. Finally, took pliers and loosened every clip on the turbo coolant hoses and wiggled the hose on it's connection. Hasn't leaked a drop since. Go figure.
 
quote:

Originally posted by SilverGGA:
Titan: Yes, I've read about others experience with GC in Subaru WRX/STi and it doesn't burn off. This is one of the main reason I want to use GC next, because I've been using ~0.5 qt every 5k miles. While this is totally fine, I'd prefer an oil that doesn't burn off.

I did require approx. 0.5/quart of green GC in my STi over a 5,800 mile OCI...hopefully your consumption will be lower still. I'm OK with a bit of consumption, but certainly would prefer zero consumption over a 5k interval.
 
Mine doesn't burn off unless I run at 85+ mph. It's a 2.5, normally aspirated engine. At 85+, it burns down to about 1/2 way between full and low, and stays there. Might try not adding any make-up oil and see if your's will stick and stay at about 1/2 way. Just a thought....
You Turbo guys may have a tendency to drive a bit harder than me on a normal day, so, it may not require 85+ mph to get the same slight drop that stabilizes somewhere between full and add.
 
Replace your radiator cap... I had my system pressure tested 2x by the dealership, and both times, no leaks were detected... so it dawned on me, where do they pressurize the system? Through the radiator cap connection! Replaced my radiator cap, and the slight coolant leak I was detecting when parking over snow disappeared for good. Try it out, it's a cheap solution (what? $5 at AutoZone?)
 
Thanks guys for the coolant advice. Checked all the small hoses out of the expansion tank and they looked fine. Will need to look at the tubes going to the intercooler later. Also wiped the tank cap clean so that if it boils out of there I'll be able to see the residues.

The level has been right at the middle between the max/min marks for a couple of months. I wonder whether it was just really cold out when I thought it was low. Need to keep an eye on it.

Titan: Yes, I've read about others experience with GC in Subaru WRX/STi and it doesn't burn off. This is one of the main reason I want to use GC next, because I've been using ~0.5 qt every 5k miles. While this is totally fine, I'd prefer an oil that doesn't burn off.

Quattro Pete: Yes, the 10w-40 weight of M1 EP has been discontinued. They don't even show it in their website anymore. They are keeping the 5w-30, 10w-30, 15w-50 though.
 
Amsoil AMO 10W-40 will be good for your turbo, actually the 15W-40 AME product would be cheaper.

I don't think you have too many ultra-cold start problems in San Jose, eh?

Cheers!
 
Status
Not open for further replies.
Back
Top