I'm curious about how the RD30 is different from RD20 in terms of addictives and film strength, etc. Because if they have similar properties and being a heavier weight, would that be more ideal for the Evo?

 

What's the pricing like on the RD 5W20? Decent? The nice thing about using Mobil 1 is that one of the auto chains have their $30-35 oil + filter deal almost every month. At that price, changing frequently isn't a big deal. Start doubling that, though, and it's going to get expensive fast.

I have 5qts + a filter of Mobil 1 Extended Performance I got for $29 (current sale at Advance through the end of the month), but after that I may be looking to make a change.

 

Price on the RD 5W20 is about 10-11 bucks a quart, which is only about 20 cents more than the SSO. However, I got a guy that I deal with that sells at dealer cost, so it's more in the neighborhood of ~8 bucks a quart. Oh, and I found more info on the wear scar test results regarding the SSO vs the ASL. In the more grueling test, the SSO does outperform it, but only marginally. They are about the same. However, there is much more to an oil the wear scar test results...

There is shear stability, ability to handle fuel dilution from exotic fuels like alcohol and nitromethane, and sometimes you have to give up a little in one area to gain more in the other. Perfect example, the RD 5W20; it gives up a tiny bit (and I stress the word tiny) of anti wear at low temps (.490 vs .406 for the SSO) for better shear stability (3.6 vs 3.2 for the SSO), more horsepower, ability to handle contact with exotic fuels, and better overall protection at high temps and periods of sustained abuse.

As great as the SSO is, it's a street oil. It can handle mild track use better than mobile one or any other street oil, but it's not a racing oil and if you are gonna be running at the track or driving your car very hard, the RD series oil is a better choice. The only difference in terms of streetability is the extended drain intervals that are possible with street oriented oils like the SSO but again, you shouldn't be doing that on an EVO anyway.

The reason for this, if anyone was wondering, is because the SSO has high TBN and detergent additive packs, which are replaced in the RD series oils by more performance and shear stability oriented additive packs more suitable for racing conditions. I have talked in detail about this with Oil Doc, who has talked in detail about this with the tech department at AMSOIL and this is what was said. In all reality, AMSOIL RD oils are overkill for most people, but I'm an overkill kinda guy .

 

Additives are going to be very similar; it's the weight that differs more than anything. The 30 weight is going to be a little more shear stable than the 20 weight, but the RD20 is more shear stable than any 30 weight street oil and even some 30 weight race oils. Taking this into account, you have to look at the pros vs cons, and in this case, there is a lot going for the 20 weight. Lighter oils will make more HP because they are thinner, flow faster, and create less drag on the internal components.

So, if you have a 20 weight that can do this AND provide more protection than a typical 30 weight, that's a win in my book. I'd say that for road racing in an EVO with up to 500 hp, the RD 5W20 is the best choice. At power levels beyond that, like drag setups that are running crazy high HP, the RD 10W30 is the best choice. Remember, you have to think... APPLICATION SPECIFIC. Get what is ideal for YOUR setup, not the guy making 1000 hp. Hope this helps.

 

Thanks Dave for the info; very informative. Not sure if I am going off of SSO though.

Later, Ken

 

 

The crucial question is, are the wear metals low? A routine $20 UOA will not give you the total picture on wear metals. ICP elemental analysis (which is what you get from Blackstone, Polaris, etc with a standard UOA) has an upper detection limit of 10 um. Any metallic particles larger than that will not show up on a standard UOA.

Polaris states it clearly on their website:
"If you depend solely on Elemental Analysis by ICP to detect wear metal concentrations, you may not always know when a catastrophic failure is in progress."

http://www.polarislabs1.com/icp-only.htm

If your UOA shows 5% fuel, and "only" 35 ppm iron, it may be premature to say that the fuel is not causing accelerated wear. The true iron concentration may actually be much higher, indicating excessive wear on the camshaft, timing chain, etc.

 

Hey Sub, Just so Giz doesn't have a heart attack here when you (quote) use terms like "catastrophic failure" and suggest he may have a big problem, I would like you to comment on the changes in the wear metals that he did observe. Specifically, Fe dramatically decreased as well as most of the metals except three, Ca, Boron, and one other I cannot recall. So wouldn't it be reasonable to say (1) these reductions are indicative of a lessening wear problem and (2) the larger particles not analyzed probably decreased as well?

Later, Ken

 

We can state without dispute that the concentration of iron particles under 10 um went down with the 2nd oil change. We have no clue whether total iron concentration went down, up, or stayed the same. In the absence of data, anything said about the larger iron particles is pure conjecture. Engine wear appears to have gone down, but we can't really be sure, can we? To get a definitive answer will require additional testing, over a broader particle size range.

If my fuel dilution increases, but my wear metals decrease (as determined by ICP), this discrepancy would have me wondering if I am getting the whole story.

To get an idea of what analytical methods are available, look at figure #3 in this document:

http://teraspeed.com/oil/AI%2520M%25...520Reprint.pdf

 

Here is a link to a relevant thread at BITOG: "Is testing for Fe an indication of engine wear?"

http://www.bobistheoilguy.com/forums...392536&fpart=1

 

Thanks Sub for expanding further on the complexities of interpreting engine oil. That said, I would agree with your scenario, "If my fuel dilution increases, but my wear metals decrease (as determined by ICP), this discrepancy would have me wondering if I am getting the whole story". For Giz's oil though this did not happen, his fuel dilution went down and so did most of the metals. In addition, you did not address my question regarding the relationship between between small and large particles i.e., if the smaller Fe particles go down in sequential oil changes, will not the larger Fe particles also go down?
Finally, from the thread in Oilbob, Greaser said: "If you have high Fe numbers and the other elements are raised then there is a problem.If you have just high Fe then there probably is another scenario at play." Giz had low and significantly decreasing Fe as well as the other other wear metals as well so, if I read Greaser right, Giz does not have a problem?

Later, Ken

 

It looks like I've turned into the topic of conversation

While I do think there's some underlying issue with the fuel dilution, my results are not far out of line with others in the spreadsheet. Look at SteveX's results, for example. I have a few wear metals that are higher, but they're not out of line compared to others in the sheet. While there was debate earlier about how fuel dilution doesn't accumulate with oil age, I would think wear metals do. Consider that my change interval up to this point was the factory-recommended 5k (30% longer than the next closest sample), and things do not seem quite so bad. My Iron levels are in the middle of the pack and aluminum/copper are among the lowest (both indicated as important by BITOG).

While tuning does not seem to eliminate the fuel dilution problem, it appears to have an effect on reducing wear metals. I haven't had a chance to include Q15H's tuned set into the spreadsheet yet, but his and SteveX's wear metals are quite low.

Assuming I was concerned, what test would even be performed next and who would I look to to do it? I see a wide range of possible tests in the posted documents, but no suggestions on where to go from here.

Mitsubishi is, as typical, clueless. I'm somewhat timid about taking it back for them to poke around at when they don't know the cause. They have no idea what to do about it. I've let dealerships do that for cars in the past where they just start replacing things in hopes of accidentally finding the problem and it never turned out well. I'll probably try to handle it myself.

I'm drastically reducing my oil change intervals. I have an intake and exhaust that are going on in the next month or so, but more importantly a custom tune is scheduled. I plan to change my oil just after that, so I'll probably only have 1.5k-2k miles on this oil (which I will also have analyzed). Hopefully it looks better. I wonder if it would be a good idea to use a Wal-Mart jug of a cheap synthetic to drain out all the current oil. I don't have access to pressurized air, so I can't do a real flush.

Actually, this is not accurate. My fuel dilution went up from 2% to 5%. Of note: First oil change was immediately after a 40-50 mile trip, second was after a series of 5-10 mile trips. These were mentioned earlier as best and worst case conditions, respectively, for reduced fuel dilution. In addition, the second sample saw temperatures mostly in the 0 - 40 * F range for 80% of its life cycle. One other thing to note is that these were my first two oil changes, so higher wear metals are somewhat expected. In addition, the first change was stagnant for several months, a situation that can reduce accuracy of the UOA.

 

Yup, I messed up about your fuel dilution history, sorry about that Sub, but the wear metals did go down DESPITE the increase in fuel dilution which is interesting. So, yes fuel dilution is not as indicative of wear as the metals concentrations.

Later, Ken

 

Yes, and no. Depends on the wear mechanism. I've read reports where ICP results correlated with large particles, and where it didn't.

 

Dyson Analysis uses RFS (rotrode filter spectroscopy), which will bump you up into the 10-100 um particle size range. But at $99, it costs more than an analysis by ICP.