Would it hurt to add MMO to my engine?  Bought my car new and already put in 30K miles on it.  Have used mobil1 synthetic at every OC (frequency of change is about every 5K miles).  Have also used in fuel at the recommended levels at every fill up...sometimes I’d half the recommended dozage.  Engine purrs like a kitten, like new so far.

I’m not a big believer in using MMO in good synthetic oils, especially if you are running extended oil change intervals. That being said, 5000 miles is not really an extended period. You shouldn’t have any problems running MMO all the time.

If you are driving under normal conditions, no towing and not under constant short trips and stop-and-go traffic, I would suggest you bump the intervals up to 7500 miles and add the MMO with about 3000 miles to go before the next change. I do this only I put between 10,000 and 12,000 miles between oil changes with extended service oil.

It’s all up to you.....but personally, if you’ve owned the car since new, and have kept up on the maintenance, you probably “really” don’t need to use it in the engine oil.......as mentioned, MMO is compatible with synthetics, but MMO themselves don’t recommend keeping MMO in the crankcase for more than 3000 miles....so if you want to add the MMO to the “last 3000” of your intended OCI, I don’t see a problem with that.....

And this will be the first time I’ve ever recommended this LOL....simply because yes, under “most” circumstances it’s best to use MMO in freshly changed oil....but in the case of a synthetic, surely you want to take the OCI out to 5000+ miles.....and adding at the start, would have you changing it at 3k (if you followed MMO’s guidelines anyways).

Also note, keep an eye on the oil level after adding the oil, there’s been some who have experienced “oil burn off” when using MMO....myself included.  So even if you add it at the last 3k of your OCI, keep an eye on your oil level, say every other fuel up - I always keep the pump attended, and will pop the hood before gassing up, and check the oil level AFTER fueling up, giving the oil plenty of time to drain down to the pan while I’m pumping

Orangedotfever - 23 September 2011 01:49 PM

I’m not a big believer in using MMO in good synthetic oils…

If one were using a 0W-20 synthetic oil would MMO provide a benefit during cold starts?  If the answer is no then what about 5W-20? 

There is no question that MMO would help during cold starts when using 10W-30, 10W-40, 15W-40, 20W-50, etc. 

I’d like to know if there a weight of synthetic motor oil that wouldn’t benefit from MMO during cold starts.  By cold I mean sub-freezing.

SparkPlug - 01 December 2011 04:53 PM

Orangedotfever - 23 September 2011 01:49 PM

I’m not a big believer in using MMO in good synthetic oils…

If one were using a 0W-20 synthetic oil would MMO provide a benefit during cold starts?  If the answer is no then what about 5W-20? 

There is no question that MMO would help during cold starts when using 10W-30, 10W-40, 15W-40, 20W-50, etc. 

I’d like to know if there a weight of synthetic motor oil that wouldn’t benefit from MMO during cold starts.  By cold I mean sub-freezing.

MMO is a straight 5 weight oil so adding it to a 5W** oil will do nothing to cold starts (from a viscosity standpoint). Adding it to a 0W** oil could actually hurt cold start performance. That being said, at the ratio you will be using MMO, I doubt that you would ever notice.

There seem to be differences of opinion as far as MMO’s weight / viscosity properties are concerned.

Posted on BITOG: According to the (MMO) VOA, it is a 2.64cst oil. The MINIMUM for a 20 weight is 5.6, SAE 5 is 3.8, so this stuff would be what, SAE 0?

Posted on BITOG: ...Place a bottle of MMO in the freezer and see what happens, then do it with your favorite 0W20 oil.

SparkPlug - 02 December 2011 03:33 PM

There seem to be differences of opinion as far as MMO’s weight / viscosity properties are concerned.

Posted on BITOG: According to the (MMO) VOA, it is a 2.64cst oil. The MINIMUM for a 20 weight is 5.6, SAE 5 is 3.8, so this stuff would be what, SAE 0?

Posted on BITOG: ...Place a bottle of MMO in the freezer and see what happens, then do it with your favorite 0W20 oil.

Rich Kelly, the old senior tech on here said in a previous post that MMO was a straight 5 weight oil. You can’t compare straight weight oils to multi-grade oils at variable temps anyway. Apples to Oranges. You just asked about it at start up in sub freezing anyway.

Duplicate post removed.

Orangedotfever is correct.  MMO is formulated with an oil blend equivalent to a 5 weight oil.  Also, the oils cannot be compared due to the nature of the formulations between multi-grade oils and straight weight oils.