Mixing Stern Drive Lube viscosities ?
 

Just drained and refilled my Merc 4.3L sterndrive.
I bought 1 qt of Mercury SAE-90, but it was not enough. I can see this in the engine reservoir container, that it is about 4-6 oz, below the full line.

SAE90 is not cheap at $16 a quart. Question..... I have some 85W x 90 drive oil I used last year for a Outboard, can I add this to the current straight
SAE-90, without causing any issues ?

I'd buy another quart of SAE90 to add, but I'll be selling the boat in the Spring.

Thoughts?

'The wrong oil is better than no oil'

Walmart.com says the Gilford Walmart has quarts of Quiksilver high performance sae-90 gear lube for $9.97/qt ..... and probably has Super Tech 80w-90sae marine gear lube for $6.28 .... and the out-drive will never know the difference!

5-stars, 10/20/2019: "Good price and I like the color of the oil (SuperTech). Easy to see if you have any water in your oil." ..... BigDaddy

I dont mix different weights. I dont even like mixing same weights of different brands. Buy the other quart at $16 and save the remainder for next year..............

Yeah, don't do that, $16 is a lot cheaper than a lower end.

Just to repeat... 'I'll be selling the boat in the Spring'.
Only need about 6oz to fill reservoir to full level.

Thanks !

It's $16 to do it right. Add it to the price when you sell it.

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That sounds a little sleazy to me....

Mixing Stern Drive Lube viscosities ?
 

What would you do if you were keeping the boat?
Do the same for the next guy.

Its $16, Jeez…
I put a set of tires on a car once for my buyer.
$16?
Do you squeak when you walk? :)

BTW, thank you for the referral, Kevin!


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$16 is the price of a 4 pack of micro brewed beer. Why screw the next guy. I’d be embarrassed to say that.