Oil oil oil oil oil?????

[northern]

we use 40 weight oil at 1750 hours the engines use 1/2 quart in the 100 hours between oil changes. It does take longer to drain but that allows one to have an extra pop and relax. Used to use 25/40 in twin V6s it seemed to work fine also. Use 40 weight because the manual said to.

 

[JohnGordon]

I think I have read every oil thread on this sight, and no one has ever mentioned Valvoline racing oils. They are at the top as far as viscosity breakdown, sludge protection and also for the amount of ZDDP. Granted, this is not a marine oil, so it doesn't have the corrosion additives, but it works for me because I trailer my boats so they always come home and dry out in our building. If I left the boats in the water for more than a couple of weeks I would run marine oil.

Just my .02

John
1987 268, 454 Mag, Alpha 1

 

[skolbe]

Have had no problems whatsoever with a quality "dino" Straight 30W, 40W, or the standard-grade Merc 25W-40.

The "extended drains" argument doesn't exactly hold water as most folks who boat where winter exists just change their oil annually anyway at lay-up.

Based on what I see on my dock - I think there are plenty of extended drains, meaning they don't change their oil annually.

 

[mike472]

http://www.mercurymarine.com/engines/inboards/inboards/mx6-2horizon_specs.php

Check out the above link. They are recommending 20-40W full synthetic for my engine the 6.2 horizon. I would follow their recommendation for two reasons: I haven't seen this specific viscosity offered in mineral or synthetic and it's available online for about $29/gallon. See what oil is recommended for your engine on this site. Why mess with what works from the manufacturer?

 

[Gofirstclass]

Delo 400LE 15W-40 in the new boat and I'll change it every 150 hours which will be about every 15 months.

My last Sea Ray (330 Dancer) I used Pennzoil 10W-40 and changed it twice a year.

 

[paulswagelock]

So think about it, Mercruiser said no way to synthetics, period. Until they sold their own recently.... Theirs is not a great choice for boats without catalytic converters. They claim the oil was developed to protect those cats. Guess how - they remove the additives that provide high pressure boundary layer protection (Zn, P) for example. That protects the cats, but provides less protection for the engine.
Mercruiser said no way to multiweight oils but have always manufactured one (25w40). And no, you can not blend a 25 and a 40 and call it a 25w40 as they claim, that is marketing hype. 25w40 means that it flows like a 40 weight at 100 degc and a 25w at 0degc. The problem is, even at summer temperatues, a 25w oil is too thick to flow readily, so you are bypassing the oil mostly until it warms and thins.
Lastly, all oils prevent corrosion, additives only help a little. I would rather have a stout HTHS number than an NMMA certification.
So, use what you want, but with research most lean towards good diesel/HDEO oils in the 15w40, 5w40, or straight weight flavors such as Delvac, Delo, and Rotella.

 

[thomas]

Here are a few tests, I am not saying that Mercruiser Oil is bad, I am saying that just because it says mercruiser on the side of the bottle does not mean it is superior to everyone elses product. Both Dealers and the Manufacture will recommended their product only because they make money off of selling it. I work at a Mercury Dealer and we recommend it because if we recommended a different brand like AMSOIL we loose out on the $10 profit we would have made if we recommended mercury oil. Again Mercury oil is not bad, it is actually a very good oil, but if you want the best then mercury oil is not the oil for you.

If it's all about the money, I think you should talk to your boss and carry AMSOIL at your dealership. That way the store makes a profit, And you get paid. (Imanage that)

 

[Dick Whetstone]

I like and use Rotella 15-40 in my 2001 270 with single 7.4. I use Rotella in my 1986 Glassmaster 21 foot Regency with 5.7 Mercruiser. I use Rotella in my 1964 "classic and original and like new" Glassmaster 17 foot runabout with 153CID 110HP Mercruiser. I have never done anything to any of the engines, except routine maintenance.

I think the Mercruiser dealers recommend Mercury 25-40 because they make a nice profit on it, and I get the feeling that Mercury may threaten to "pull" their dealership if they recommended or sold anything else. Did you ever go to a Chevrolet or Ford dealership and have them recommend AutoZone parts??

Mercury, Rotella, Delo, Havoline, Valvoline, Amisol, etc, etc are all good oils. IMO the most important thing is that you use a "good" oil and change it and the filter often.

99.9% of marine engine failures will be due to something NOT related to the brand of oil you use, assuming it is changed regularly.