Mixing Stern Drive Lube viscosities ?

bigdog · 09-30-2021, 09:25 AM

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?

root1 · 09-30-2021, 09:27 AM

'The wrong oil is better than no oil'

fatlazyless · 09-30-2021, 11:27 AM

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

SAB1 · 09-30-2021, 11:50 AM

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..............

ITD · 09-30-2021, 02:30 PM

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

bigdog · 09-30-2021, 05:18 PM

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

Thanks !

thinkxingu · 09-30-2021, 05:40 PM

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

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ITD · 09-30-2021, 07:29 PM

Quote:

Originally Posted by bigdog

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

Thanks !

That sounds a little sleazy to me....

LakeDad · 09-30-2021, 07:54 PM

Quote:

Originally Posted by ITD

That sounds a little sleazy to me....

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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SAB1 · 09-30-2021, 08:28 PM

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

09-30-2021, 09:25 AM	#1
bigdog Senior Member Join Date: Apr 2006 Location: Central MA-Gilford Posts: 1,459 Thanks: 357 Thanked 126 Times in 100 Posts	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?

09-30-2021, 11:27 AM	#3
fatlazyless Senior Member Join Date: Apr 2004 Posts: 9,168 Blog Entries: 1 Thanks: 310 Thanked 1,103 Times in 812 Posts	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 __________________ .... Banned for life from local thrift store!

09-30-2021, 05:18 PM	#6
bigdog Senior Member Join Date: Apr 2006 Location: Central MA-Gilford Posts: 1,459 Thanks: 357 Thanked 126 Times in 100 Posts	Just to repeat... 'I'll be selling the boat in the Spring'. Only need about 6oz to fill reservoir to full level. Thanks ! Last edited by bigdog; 09-30-2021 at 05:18 PM. Reason: spell

09-30-2021, 09:27 AM	#2
root1 Senior Member Join Date: Jun 2020 Location: Alton Bay Posts: 69 Thanks: 24 Thanked 23 Times in 17 Posts	'The wrong oil is better than no oil'

09-30-2021, 11:50 AM	#4
SAB1 Senior Member Join Date: Feb 2012 Location: Tuftonboro Posts: 1,275 Thanks: 196 Thanked 336 Times in 244 Posts	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..............

The Following User Says Thank You to SAB1 For This Useful Post:
DotRat (09-30-2021)

09-30-2021, 02:30 PM	#5
ITD Senior Member Join Date: Apr 2004 Location: Moultonboro, NH Posts: 2,953 Thanks: 484 Thanked 703 Times in 393 Posts	Yeah, don't do that, $16 is a lot cheaper than a lower end.

The Following User Says Thank You to ITD For This Useful Post:
DotRat (09-30-2021)

09-30-2021, 05:40 PM	#7
thinkxingu Senior Member Join Date: Jul 2014 Posts: 6,540 Thanks: 1,184 Thanked 2,176 Times in 1,353 Posts	It's $16 to do it right. Add it to the price when you sell it. Sent from my SM-G950U using Tapatalk

The Following User Says Thank You to ITD For This Useful Post:
SAB1 (09-30-2021)

09-30-2021, 08:28 PM	#10
SAB1 Senior Member Join Date: Feb 2012 Location: Tuftonboro Posts: 1,275 Thanks: 196 Thanked 336 Times in 244 Posts	$16 is the price of a 4 pack of micro brewed beer. Why screw the next guy. I’d be embarrassed to say that.