Belray MC1 oil - caused failure?

[Reuel]

I have been using Belray MC1 synthetic oil now for 20 years mixed at 50:1. I use it in my chain saw, leaf blower, weed eater, 1984 RM125, 2003 YZ125 and 2000 CR250. I have had zero problems. Whenever i took apart a topend there was always plenty of nice blue oil coating the rod/crank etc. My buddy bought a used 2001 RM125 about 6 months back. He never owed a 2-stroke before and like any new comer would do he was mixing 32:1 natural oil. It smoked like crazy and i bugged him for months to switch to Belay and mix it 50:1. Actually Belray says you can mix it at 100:1 but I never have. So anyway he finally gets some MC1 and uses it. The first ride out his rod bearing on the crank destroyed itself. Now I feel responsible since I talked him into switching. Was this just bad luck-bad timing or have I just been lucky all these years? Anybody else have any nightmare stories about MC1 oil? The only negative thing i have heard from a local racer is that he said he did not like it because it seperates from the gas when sitting even for a short period of time. I spose i can pour some in a glass jar and keep an eye on it. Anybody have any comments on this oil?

[Big Maico 393]

Just like you I've run Bel-Ray MC1 in every 2 stroke that I ever owned with no problems.

Even before I went to work for Bel-Ray, I would say it was just bad luck or he didn't re- jet the bike properly.

[Red Rider 943]

50:1???? what, I used to run that oil, and i used it at 32:1...

[superrooster]

A 125.........50:1.........okay I'd say its your fault

[Spitfire]

I've been running Amsoil in my 125 for a couple months, with zero problems. I ran Amsoil in my 250 for a week or two (riding every day), with zero problems. I ran out of Amsoil one day, so I used some Bel-Ray MC1 at 32:1, and my crank bearings blow out 10 minutes into that ride! Come to find out.....the bearings were blown because of oil starvation, needless to say, I won't be running MC-1 anymore!

[quadfather03]

Im with big maico id say it was something else and you shouldnt doubt it if you have run it for years. I swear by belray i use h1R in all my bikes it is rated at 40:1 but the mc is rated at 50:1 on every engine. I wouldnt hesitate to run mc1 if i didnt like this H1R so much. Id say it was another problem.

[KX02]

Well, if you have been using bel ray for 20 years at 50:1 that pretty much settles it. I don't know why people insist that it would blow an engine or something at anything less than 32:1. I mean don't you think it would be kind of bad for bel rays business if they had tons of people blowing their motors while bel ray laughed it up? For the record I run Castrol TTS at 40:1 in my 125, I've ran it from 32:1 to 50:1 and just thought 40:1 was the best overall.

[Vintage Dave393]

This is not the oil's fault. It could be a case of the previous oil and the MC1 not being compatible or it could have just been time for the rod bearing to go. It is a 4 year old 125 and it sounds like maintenance was not high on your buddy's list if he was not even running 2 stroke oil. Chaulk it up to a learning experience and move on.

[KKXR400R]

Bel ray makes some great oil. I'm calling it right now, It was probably time that the bearings to go.

[KKXR400R]

he was mixing 32:1 natural oil.

I just read this....when I bought my cr250 i was using golden spectro at 32:1 non synthetic. It spooged like crazy and was driving me crazy. A friend of mine told me about motul 800 (full synthetic) and said to mix it at 32:1 until the old premix blew out(about 2 tanks of gas). I then switched to 50:1 and have run all the bikes,including tracys 125, for the last 2 years no problems. here is a pic of tracys cylinder after breakdown

It could be a case of the previous oil and the MC1 not being compatible or it could have just been time for the rod bearing to go.

Did we hit the head on the nail?

[Reuel]

Well like you said, I have been using it for 20 years with no problems. I will keep using it and chaulk it up as bad luck for him.

[Mainjet2001]

Read Vintage Dave’s post again.
It's spot on. There is nothing wrong with MC1 and after 4 years, the thing is worn out.
Blaming the failure on MC1 is just incorrect. If a 2 stroke is ridden around slow (no heat/slow throttle) with no oil in the gas, the lower rod bearing is the first to go in many cases.
One more thing, there is not a 2 stroke racer/rider worth their salt that does not shake up their gas mixture before using it.

[yzernie]

I agree about the possibly worn out engine and the oil not being responsible for the failure. I do believe however, that 50:1 in a 125 is a tad lean...especially since MC1 is not a true synthetic oil.

[ProAMA725]

It shouldn't even be a question of oil. If the oil was doing that, Belray would have pulled the product. They test everything. 125's that are 4 years old will have cranks go out right about now. Just the way they work. He also could have had an airleak or anything else that made it go. I personally like 40:1 as well, but that is just me. 32:1 is just too thick and 50:1 scares me a little. But don't worry, it wasn't the oil. Although, Ernie is correct. When running that thin of a mixture, definitely would recommend a fully synth oil. 40:1 is the thinnest I would go on any bike with normal 2 stroke oil.

[ossagp]

I am not a big fan of MC1 for extended high rpm work. most mx and trail riding it works fine for those I know at 50-1.

Was his Suzuki "dry" upon teardown, or like your cr250 Reuel?