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Author Topic:   Mixing Gear Lubricants
guppy posted 11-04-2008 04:38 PM ET (US)   Profile for guppy   Send Email to guppy  
In the process of winterizing my 2006 Mercury 90-HP motor, I used some Quicksilver High Performance gear lube left from last year, but it didn't quite fill the lower unit. I bought what I thought was the same stuff. While I was pumping it in I saw that it was brown not green. So I looked on the bottle and it was in fact Quicksilver Premium gear lube, and [the lable advised] to not mix with the High Performance stuff. I figure it will be alright through the winter, but I'm not sure what to do next spring. Should I drain the unit again and add one or the other or just leave it as is and assume that the do not mix warning is a scare tactic?
fishgutz posted 11-04-2008 06:06 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
If you mix those two lubricants and run the motor you will have a massive explosion.

OK, it won't really explode. I did the same thing a few years ago. Then I asked my dealer and mechanic. He said that the two lubricants should not be mixed. They are not compatible. He also couldn't tell me exactly why. Maybe it is like mixing oil and water. It could foam up. Who knows? You'd think you'd be mixing a little of each together if you changed from one to the other. There is always some left on the gears and inside housing.

Lesson learned. Now I make sure I buy the right stuff.

Personally, I don't think it makes a difference.

Does that answer your question? I didn't think so.

Bella con23 posted 11-04-2008 07:15 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
This is on the Mercury web site

Should I use Premium Blend or High Performance gear lube in my sterndrive?

High Performance gear lube is required in all Bravo and Alpha I Generation II sterndrives. It is recommended for use in all older sterndrives as well. Premium Blend and High Performance gear lube should never be mixed. Be sure to drain the unit completely if switching from one type of lube to the other.

I believe the reason is that the Premium Blend is a petroleum product and the High Performance is a synthetic.

guppy posted 11-04-2008 07:58 PM ET (US)     Profile for guppy  Send Email to guppy     
Well, I was going to start the motor behind a blast door in the spring anyway; as I do every year.
The different formulations makes sense as to why they shouldn't be mixed. I guess I'll make the extra effort and drain the thing again in April. Thanks guys for the info.
macfam posted 11-04-2008 08:36 PM ET (US)     Profile for macfam  Send Email to macfam     
Simple and cheap.
Drain and refill with Mercury High Performance (blue-green) gear lube.
Case closed.
wbullwin posted 11-05-2008 09:31 AM ET (US)     Profile for wbullwin  Send Email to wbullwin     
I have also read and heard from mechanics to never mix since one is synthetic. Since you have to drain it anyway and buy new, I would pull the plugs now and let it drain for at least a few days and then fill. If you are anything like me, you may forget to do it or the time required to completely drain it might be precious moments on the first nice boating day in the Spring. I always leave a boat in the Fall so all I have to do is hook up a freshly charged battery and go!
glen e posted 11-05-2008 10:00 AM ET (US)     Profile for glen e  Send Email to glen e     
the blue green stuff is the stuff to use...for the record, none of these are synthethic - the hi perf is a syn blend with dino.....but will offer protection better if water invades the lower end...
Ridge Runner posted 11-05-2008 02:54 PM ET (US)     Profile for Ridge Runner  Send Email to Ridge Runner     
Pull the plug and let it drain all winter. In the spring just add about a pint of High Performance to the top hole and let it drain straight through, this should flush out any Premium gear lube that might still be in the unit.
swist posted 11-05-2008 04:29 PM ET (US)     Profile for swist  Send Email to swist     
I'll bet it wouldn't make a damn bit of difference if you ran a mix for a season.

Of course, I'll let someone else's boat be the guinea pig :-)

Buckda posted 11-05-2008 04:54 PM ET (US)     Profile for Buckda  Send Email to Buckda     
I would not let it drain all winter as one poster suggested...If you are the type who may forget to change it in the spring then just change it now.

If you won't forget, then you can wait. I would not leave my gears exposed to moist winter air for 3 or 4 months...that's just an invitation for corrosion. Sure, I know that the gears will likely remain protected by a film of oil....but why would you run any risk when you can easily have the gears bathed in oil?

contender posted 11-05-2008 07:36 PM ET (US)     Profile for contender  Send Email to contender     
I do not think it will matter for the season, anyway engines can't read...
jimh posted 11-05-2008 08:07 PM ET (US)     Profile for jimh  Send Email to jimh     
There seems to always be a warning or advisory notice not to mix greases. Apparently the qualities of a grease are modified in the presence of other greases, so when two greases are mixed together you cannot be certain that either of the greases will retain its original properties.

Will a mixture of two greases form a compound with substantially different properties? Who is to say? It does not seem reasonable that contamination of one grease with a small amount of another very similar grease would be catastrophic. I'd tend to forget about it and run next season. If you get worried, change it in the spring. No much is going to happen while the engine sits idle all winter.

wbullwin posted 11-06-2008 09:57 AM ET (US)     Profile for wbullwin  Send Email to wbullwin     
Is the risk of ruining a lower unit worth the $10 for a quart of the correct fluid and half an hour of time over a few days letting it drain? Unless someone out there is a petroleum chemist and can give an opinion on this, I think you are taking a big chance leaving the mixture in there.
davej14 posted 11-06-2008 10:58 AM ET (US)     Profile for davej14  Send Email to davej14     
Why would you want to risk any potential damage when the cost and time required to eliminate all risk is so low? Mercury must have a reason for their warning statement. Just because you make it through a season does not mean that you haven't shortened the design life of the gearbox. Change the oil and you will sleep better at night. Do it now and you won't have to think about it.
TransAm posted 11-13-2008 07:52 AM ET (US)     Profile for TransAm    
If your 2006 motor is still under warranty, I would drain and re-fill with the correct lube. Since Merc's literature clearly states not to mix, I would not give them an excuse to disavow a warranty claim should you have a related or unrelated problem and they discover the lube mix. For 15 minutes of time and a few bucks for lube, make the change.
Chuck Tribolet posted 11-16-2008 08:43 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
If you put a sacrificial quart of High Performance in it,
do run the engine on the muffs for a while. That will do a
better job of flushing the Premium out. Then drain and
and put a new quart of HP in.


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