Royal Purple 10W-30 Subaru WRX 5022 Miles

[edhackett]

Here's the latest UOA on my WRX.

Royal Purple 10W-30
5022 miles on oil
20,028 total miles
Pure One oil filter
OEM air filter
No make-up oil

Al- 3
Cr- 1
Fe- 4
Cu- 3
Pb- 2
Sn- 1
Mo- 134
Si- 4
Na-2
Ca- 2231
Mg- 5
P- 816
Zn-966

Viscosity 56.2
Flash 370
Insolubles 0.3
Fuel
Eat your hearts out GM owners.

Actually, I have a 1990 GMC K2500 which gets fed Delo 400 15W-40 and is driven less than 3000 miles on its yearly oil change.

I wasn't going to do an analysis this time, since it seems I had found a good match for the WRX. I noticed that the oil looked a bit cleaner this time, and consumption was half of what it had been (~4 oz.), so I was curious.

Wear is down a bit, and the insolubles are the lowest that I have seen so far. Looks like it's getting broken in.

The interesting thing is that the Mo and Ca numbers are about 25% higher compared the previous two intervals and the VOA. It looks like RP is tweaking their formula.

to Subaru and Royal Purple

Ed

 

[Chris B.]

I wish my UOA's were this good, congrats! But hey, my LS1 Z28 might show more wear but it will eat your WRX alive at the drag strip!

 

[Patman]

Very nice wear numbers!

Yet another RP report which thinned out though, very disappointing. A synthetic 10w30 should not thin out this easily, turbo car or not. You don't see other good synthetic 10w30s thinning out in the WRX (which we know is easy on the oil) RP needs to tweak their formula so it does not thin out so easily.

Here is a Mobil 1 10w30 UOA in a WRX, with more than 5k on it, and the viscosity was still 10.0cst:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000718

[ November 20, 2003, 05:46 AM: Message edited by: Patman ]

 

[Bror Jace]

EdHackett, that boxer engine must be nearly-perfectly balanced. I haven't seen a bad UOA from one of these yet ... even some which have been modded and raced!

Patman is right about the thinning.

The earlier depletion (of the molybdenum, at least) is probably due to "uptake," the bonding of the material to points of friction inside the motor. Not sure if this can apply to any of the calcium additives or not.

--- Bror Jace

 

[Robbie Alexander]

quote:

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Originally posted by edhackett:
Here's the latest UOA on my WRX.
-*-*

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How many runs of RP did you do, back to back?

 

[Ken4]

I was told that oil temps in a WRX are only around 80-85C for normal cruising, only on a race track will it reach >110C. So one possible reason why this WRX shows such amazing wear numbers is that this RP10w30 is really only operating at a vis@85C of 15.33 cSt (40wt).

When I installed an oil temp gauge in my own vehicle, I discovered my oil temp reaches 105C just with normal highway cruising. Im doubtful I could get as good results as Ed's using the same oil.

 

[PRRPILL]

Hey Ed. Great report.

 

[edhackett]

Chris B: How about if that drag strip is covered with 8" of snow?

Patman: I still don't believe that the viscosity loss is totally due to shearing. I'm still loosing 85 degrees of flash, which points to fuel dilution. Last time Blackstone reported 0.3% fuel. This time they reported

Bror Jace: I don't think there was any significant uptake of the moly in the early changes. The Mo in the first two UOAs matched the Mo in the VOA.

Robbie: This is the third interval with the RP. I ran GTX 10W-30 for the break-in, with changes at 600 and 2000 miles. The RP went in at 5000 miles.

Ken4: The oil temps on a WRX do seem to be well controlled. The highest that I have seen with the car moving has been 200F. That was a long uphill pull running 5-7 psi boost at 80 mph on a 100+ degree day. I have never seen sump temperatures over 210F, even in an hour of creeping along in traffic.

Jay: You are right about the design of the engine playing a major role in its wear pattern. I think I just happend to get particularly good example of a well designed engine.

The crankshaft on a Subaru 4 cylinder is less than 10 inches long between the end main bearings. It is a five main bearing engine, with translates to less than 2 inches between bearings. To say it is well supported is an understatement. It is also fully counterweighted, has chamfered oil passages, and the radiuses are undercut. In other words, it has all the tricks. The engineers are still holding the bean counters at bay.

Ed

 

[Chris B.]

I guess if you like to do cookies RWD is the way to go! I love the AWD and it would really help here in Colorado. Last winter the Camaro acctualey did well if you did not give it to much gas but AWD would be nice. On dry pavment RWD is soooo much fun!

 

[Jay]

edhackett mentioned that his sump temps were 165-175F in this post.

I think Subarus, new Honda K20 engines, and certain Volvos and Audi's give great UOA results because they are structurally very strong engines. There's very little crankshaft, or block flex.

 

[Bror Jace]

edhackett: "I don't think there was any significant uptake of the moly in the early changes. The Mo in the first two UOAs matched the Mo in the VOA."

Point taken. I hadn't closely compared UOA to VOA. Increasing moly levels often confuse some people and 9 times out of 10 it's uptake. My bad for assuming you didn't know any better.

"The crankshaft on a Subaru 4 cylinder is less than 10 inches long between the end main bearings. It is a five main bearing engine, with translates to less than 2 inches between bearings. To say it is well supported is an understatement. It is also fully counterweighted, has chamfered oil passages, and the radiuses are undercut. In other words, it has all the tricks. The engineers are still holding the bean counters at bay."

Thanks for the specifics. In your previous UOA posted here, you said something vague like: "Subarus aren't plagued by poor engineering like other makes" and I didn't really know what to make of it.

By the way, how did you find this site? I haven't checked in a while but when I did, the major search engines such as Google were ignoring us.

--- Bror Jace

 

[edhackett]

Bror Jace: I found the site through a link on one of the Subaru boards.

Ed

 

[harrydog]

quote:

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Originally posted by Bror Jace:

"The crankshaft on a Subaru 4 cylinder is less than 10 inches long between the end main bearings. It is a five main bearing engine, with translates to less than 2 inches between bearings. To say it is well supported is an understatement. It is also fully counterweighted, has chamfered oil passages, and the radiuses are undercut. In other words, it has all the tricks. The engineers are still holding the bean counters at bay."

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And here is the little beauty...
http://www.subaru-global.com/about/parts/02.html