GC 0W30 / 4, 468 miles / 2002 Subaru WRX

[nicknaz]

left most sample is GC (the newer gold kind, not the old green kind), right two samples are rotella T 15W40

couple of things i found interesting:

1 ) wear numbers are pretty much the same. the right most sample of rotella was used a track day, the middle sample of rotella is pure commuting, the left sample of GC was used in commuting and some 'mountain' driving

2 ) GC seems to have slightly higher than expected viscosity compared to other 30 weights.. any one else see this?

3 ) a some manganese.. i think this is because i'm using a 50%/50% mix of 91 octane and 100 octane to make deto go away.. previous samples had 100% 91 octane fuel

what do you guys think? I think i might stick with rotella T since its much cheaper than a synthetic oil and looks to be doing as good of a job protecting the engine

EDIT: I was planning on doing 3 samples of Rotella T versus 3 samples of GC but I forgot to get an oil sample for the third rotella change.. i have GC in the car again right now.. so at least i'll have a 2 sample comparison to base future decisions on

 

[Steve S]

Can't beat the HDEO'S .People forget that it is run in engines that cost more than our whole cars.

 

[JAG]

Do you notice any differences in engine response or gas mileage between the 15W-40 oil and GC?

 

[nicknaz]

Originally Posted By: JAG
Do you notice any differences in engine response or gas mileage between the 15W-40 oil and GC?


no difference that i can detect

gas mileage is pretty much determined by my right foot (ie 100% flat ground interstate cruising at 55mpg = 30mpg, HPDE = 7mpg)

engine response is pretty much determined by my fuel choice (ie 100% 91 octane = deto+yank timing = motor feels like a slug, 50/50 91 and 100 octane = lots of timing back (PCM apparently can add timing to optimize up to 96 octane) = motor feels great)

the only differences that i do notice are 1 ) cruising and idling oil pressure is higher with the 40 weight (duh) 2) it takes the rotella T longer to get up to operating temp (i don't have an oil temp gauge so i estimate 'up to temp' based on when the pressure needle stops fluctuating and settles into its steady state pressure)

 

[glennc]

GC is considered to be a thick 30wt.

I'm surprised by the slightly high lead, in all your samples and the averages. Could that detonation you're referring to be hammering the bearings?

The other metals look very good - and of course the oil looks good.

 

[nicknaz]

Originally Posted By: glennc
I'm surprised by the slightly high lead, in all your samples and the averages. Could that detonation you're referring to be hammering the bearings?

The other metals look very good - and of course the oil looks good.


maybe? i've trolled the forums here and on nasioc for other UOAs from 2.0L WRX and it seems like my UOAs are consistent with other subes, so i'm not sweating it too much...

also i've read on other threads that Pb starts to get worrisome if its like... an order of magnitude more.. say.. 100 ppm.. ?

i don't exactly granny the car (i'm not a 'big launch' or 'slam gears' kind of guy but i certainly let the motor rev and dig into the boost fairly often) so its not surprising there is 'some' wear

 

[glennc]

Well I think you'd have cause to be worried well before 100ppm. Somewhere in the teens or twenties would be enough to indicate a problem in most engines. Seven is hardly high, just not the low values you usually see with today's engines and oils. I'm sure it is fine. If it were mine I'd be really annoyed by detonation though. I hate detonation, even a little bit of it on a hot day bugs me.

 

[nicknaz]

Originally Posted By: glennc
If it were mine I'd be really annoyed by detonation though. I hate detonation, even a little bit of it on a hot day bugs me.


yes, i agree with you completely. in fact detonation annoys me so much that i purchase at least 7 gallons per week of 100 octane at 5.49/gallon to compensate for the 91 octane 'premium' available in CA.

 

[SubLGT]

The 100 octane fuel may have some lead in it, even though it is sold as "lead-free".

 

[bluesubie]

It's amazing how our cars vary with consumption. Yours seems kinda thirsty (but within Subaru's standards).

I think the lead could be from the 100 octane as well (from other uoa's here). It's probably fine as long as it doesn't jump any higher.

GC has thickened for me as well, but not to an actual 40 grade oil. Oxidation?
Nice report. Push your OCI out a little bit.

-Dennis

 

[nicknaz]

Originally Posted By: bluesubie
It's amazing how our cars vary with consumption. Yours seems kinda thirsty (but within Subaru's standards).
-Dennis


yes.. this used to bug me at first but i don't see any noticeable oil or coolant consumption when i'm driving in the mountains or at a HPDE, and the consumption is within sube specs so i sort of just made peace with carrying around a quart of oil and called it a day