Any real difference? For a 525EFI

Are they not one in the same?

I thought that Mercury's trademark was "Quicksilver".

Both the same, just diferent packaging, That goes for all products that are either merc or quicksilver

Same.

Read the fine print "good for any Merc warranty issues."

I think the QS label was for the non dealers, such as West Marine, whereas the Merc Label is for the dealers.

At least what I have been told. Either way, same stuff.

Merc is really very good about warranty issues. I understand they never actually test oil and most engine oil failures are due to a failure of the oil pump; a leak or yes...somebody forgot to put the oil in. It is not uncommon for them to fix something even if the engine is a bit out of warranty.

They do not make their oil...it is not a true multi-vis oil...it pumps hard when cold and offers about the same protection when hot as any ordinary 40wt conventional oil...Merc says to use the same oil in everything from a V-6 to their 1075's. Go figure. I would not get too comfortable with it and anything beyond 496's is probably better off with 20W-50 Kendal racing if you want conventional.

Just my .02

Expensive and not worth the $$ in my opinion.

Now Mercury Gear HP is a very good product...I would not push too hard to switch from using it unless you are inclined to do so. The money here is best spent on drive showers which Merc should include anyways.