VP Fuels U4.2 and MRX01 Opinions

I am still searching for opinions on U4.2 and MRX01 fuels, as I need to order one of these days since they stopped making U2. Any and all fuel specific insight is appreciated.


Any leads on old stock U2 in the md/va/pa/wv is appreciated too!

big fan of vp street blaze 100 unleaded ....dont like the crap u4 leaves in my carb

what are you wanting to use it in?

neither has enough octane for a modded 2 stroke.

I dont know of any u2 around, but i know of about 25gal. of u4 right up the road from me. If you are interested let me know. They are taking offers on it:thumbsup:

what are you wanting to use it in?

neither has enough octane for a modded 2 stroke.

We spoke before, but still looking for more reviews. Anyway, MRX01 with 98 octane, and U4.2 with 102 gets me to where I need to be. Both fuels, with the nod to mrx01 for being dead on, meet my requirements for a modded yz250. No sure why you think neither is high enough... please explain.

Again, any input/opinion on either fuel.


I dont know of any u2 around, but i know of about 25gal. of u4 right up the road from me. If you are interested let me know. They are taking offers on it:thumbsup:

Thanks for the info. I am really after u2, and if no more can be found, I will go with mrx01 or 4.2. According to vp's specs, u4 is too low of octane for my needs, and is different than 4.2- if I recall correctly, u4 is in the low 90s for octane, and I need 98-100 for my application.


Why not consider VP C-12, tried and tested, One of the best and consistant fuels VP has ever made.

I used that in the past, and really liked it! The reason I do not use it now is b/c I want to continue to run oxygenated fuels...

That U2 is potent stuff. When I used that I would have to drive with the windows down in my van. The fumes came out of my sealed gas can unlike anything I ever experienced with C12.

I used that in the past, and really liked it! The reason I do not use it now is b/c I want to continue to run oxygenated fuels...

I use the U4.2 and it is a lot easier to deal with then the U4. It requires little or no jetting but where I buy it here in Washington I pay about $85.00 for a 5 gallon can. We run it 50/50 with premium pump gas on a stock YZ250F mainly for the oxygen. It runs really good on this mix. I would think that the 102 octane rating of the U4.2 would be just fine for a moded bike. Just my input. :busted:

Yeah, next you won't be able to buy a 2stroke in Cali..:busted:

Oh Eddie, say its not so....

Although my 06 CRF450R is stock, my sons 07 KX85 is not. However I haven't done much to engine but milled the .020" and cleaned up the ports.

So what can I use that both can run on a 50/50 blend?

I had been using VP's C12 w/Chevron 91 pump gas.

There is a bazillion fuel makers out there.







F & L


Kemco Red X



Cool Skunk

And a cool octane calculator for mixing to a desired octane

i'm running whatever sunoco has at 50/50 for my trials bike. there race gas (not always easy to find) is 110 and 112 depending on the stuff you get.

Any other 4.2 or mrx01 opinions?

From the VP website. maybe you already knew this or maybe you didn't?

I hope it helps.



Recommended for 2- and 4-stroke applications. Delivers up to 6% more power than pump gas and any basic nonoxygenated racing fuel. Excellent for high compression road race applications. Can be mixed with MR9 to raise octane level for specific applications. Clean burning — leaves intake and exhaust valves virtually free of deposits for maximum airflow and performance from start to finish. AMA legal except Supercross and Outdoor Nationals.

* Color: Pink

* Oxygenated: Yes

* Motor Octane 98

* Specific Gravity: .717 at 60° F



The latest generation of our U4 based fuels, this fuel is a direct pour-in replacement for pump gas, with little to no jetting changes required - +2 main jets and +2 pilot jets at the most. Makes power equivalent to U4 with no sticky residue and a less pungent odor. Designed for stock and modified 2-stroke and 4-stroke applications. U4.2 passes AMA amateur fuel rules and is perfect for club level racing, CCS, WERA and AFM. U4.2 makes up to 6% more power than pump gas.

* Color: Blue

* Oxygenated: Yes

* Motor Octane 102

* Specific Gravity: .784 at 60° F

Thanks for the info! I found a few pails of u2 north of me, and just picked up another 30 from Lees Performance in Newport News. Thanks for the leads on the fuel- looks like I am stocked for a bit!!!


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