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'01 E55 AMG
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Discussion Starter #1
So I decided to change from Mobil 1 to Royal Purple oil due to my conversion with Kyle at RP. RP 10w40 is what I used since AMG engine clearances are for 40 weight oil even thou RP says 10w30 can be used it is not a 40 weight oil and AMG does not recommend using it in any of our engines. The factory says to use 8 quarts not 8.5 like the 4.3 engines use so that’s what went in. I have not driven my car to see if I have any MPG gains and if I do I will let you all know. I can say that for only having 4200 miles on my last oil change the oil was very dirty! Maybe the old owner let the oil changes go a little longer then he should have? The reason I changed my oil so soon was not knowing what the dealer I purchased my car from used. They told me it was synthetic oil, but my salesmen did not know the weight or kind so out it came.

I am starting to get used to working on this AMG at first I was worried about maintaining it not as well as one of my friends shops, but I used to work for 3 car dealerships as a mechanic and ran over 12 independent shops before I retired from that profession. I love how MB designs these cars it is very different then the American car designs of the past 20 years they all are jumping on board to copy a master designer Mercedes Benz. Working on my old MB is like working on this newer model if you have the basics it helps.

I will change my oil every 8000 miles and filter every 4000.:)
 

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technically RP can go 13k with steady oil filter changes which isn't bad. but 8-9k alone will save you lots of $$, so in reality its actually cheaper than doing cheap oil every 3k
 

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'01 E55 AMG
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Discussion Starter #3
So this week I only drove to work and back 3.5 miles each way on city streets at 35 MPH My computer said with Mobil 1 oil 9 to 11 mpg, but with Royal Purple 10w40 and Redline Water Wetter at 81F it's been 12.4 to 13.1 mpg. Tomorrow I have a highway run south to Coconut Grove then north 2 hours to Palm Beach.

I will up date the highway mph, now I drive at 70-80 mph so the mpg may be lower then others that drive slower. The best my car has hit was 22.3 mpg on every long haul I’ve done to date so I’m looking for 24+ mpg now. When I did the math mph based on fuel to miles its around 19 mpg with Mobil 1 oil. My set-up is stock with Trans filter and some trans fluid changed as well as RP in engine and rear end with new tires. Oh and a fresh waxing.

I am doing on this tank of super 93 octane the math average mpg for the whole week I will let everyone know next week what that is then off to Brazil!:D
 

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awesome. RP Diff oil (MaxGear) also makes a substantial different on MPGs, you should definite give it a try. those two together should net you better results. hope that helps.
 

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2001 E55 OBSIDIAN BLACK
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i just put in 10w30 RP yesterday..the weather in the central valley in cali can reach 110+ degrees...after reading dawson's post that he had spoke with a RP tech who advised 10w30 would work in his 55 even if he lives in miami...maybe the next time i top it off, ill use 10w40...im sure it will work here too in this hot climate...it seems to have a little more power and pulls a little harder to redline.....im hoping to attain better mpg as most members claim RP will produce...will keep u posted...

thanx all
 

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'01 E55 AMG
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Discussion Starter #7
Well, I did a 75 mile run one-way and the best my E55 computer would do is 22.3 mpg at sea level, 91F and 80 mph. maybe it's the 10w40 like RP Kyle said I won't see much with 10w40, but a lot better with 10w30. If my mpg goes up, I will let you all know. One thing is the power feels little better then before.
 

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as far as MPG is concerned I think the best improvement was from the Differential Oil b/c its so thick and RP is much better than the stock stuff they put in there. Try the Diff oil you should see better results.
 

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2001 E55 OBSIDIAN BLACK
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omeyhomey said:
for best MPG results do engine & Diff oil. hope that helps.
omey,

what weight RP diff oil did u use on your 55.......i saw 2 different weights on the shelf.....did u change your entire trans fluid too?

thanx
 

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2001 E55 OBSIDIAN BLACK
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Had RP diff oil 75w90 installed at shop. including 2 qts of RP and install came to $68....mechanic also said spark plugs need changing way before the 100k miles that the factory reccomends...gave me an estimate of $400....parts/labor..prob get that done next round..hopefully some gains in mpg will be realized after the fluid changes.
 
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