Motor oil

Scott215

Well-Known Member
Jun 4, 2022
2,154
Boat Info
2006 215 weekender 5.0 mpi
Engines
5.0 mpi alpha 1 gen 2
I have a 2006 5.0 mpi. Looking at oil today they list 25 40 for outboards. The only oil for stern drive is sierra. I want quicksilver 25 40 is the outboard motor oil the same. I don't see a difference if it is a 4 stroke. So why do they say outboard 4 stroke and not stern drive. Thanks. It actually says outboard oil
 
I have a 2006 5.0 mpi. Looking at oil today they list 25 40 for outboards. The only oil for stern drive is sierra. I want quicksilver 25 40 is the outboard motor oil the same. I don't see a difference if it is a 4 stroke. So why do they say outboard 4 stroke and not stern drive. Thanks. It actually says outboard oil
I noticed it too. Outboards are popular. It's the same. 25W40.
 
Thank you synthetic blend correct
 
I would use full synthetic. And there are better oils out there than Quicksilver. I use Rotella T6, which is overkill but gives me peace of mind.
So you say there are better oils out there than Quicksilver. What credentials do you have that make you the expert in motor oils? I’m not trying to be critical I’m just curious. Quicksilver and Mercury are the only oils recommended by Mercruiser. I would think that would be the oil of choice. Especially considering Quicksilver oil is reasonably priced at Walmart.
 
So you say there are better oils out there than Quicksilver. What credentials do you have that make you the expert in motor oils? I’m not trying to be critical I’m just curious. Quicksilver and Mercury are the only oils recommended by Mercruiser. I would think that would be the oil of choice. Especially considering Quicksilver oil is reasonably priced at Walmart.
 
I would use full synthetic. And there are better oils out there than Quicksilver. I use Rotella T6, which is overkill but gives me peace of mind.
I think mercury dropped their full synthetic in favor of the blend. And not many 25W40 oils available off the shelf.
 
Most are nothing more than General Motors engines. Mercruiser doesn't manufacture oil, They just endorse their own brand.
Actually I think they are "more" than plain GM engines. I believe the camshaft is different. They also generally work harder at higher RPMs.
 
Actually I think they are "more" than plain GM engines. I believe the camshaft is different. They also generally work harder at higher RPMs.
I rebuilt an original 357 Mercruiser last spring for my next drop in. It had a gm performance roller cam in it. A quick google search of the part number gave several light off-road applications for that cam. Really wasn't anything special in it from a stock truck TBI engine. The pistons were half instead of full dished hypereutectic's. Other than that, it used a different windage tray and intake manifold. Nothing magical.
It had lost the low hour'd block (.040 over) with a cracked cylinder wall. I grabbed a TBI and bored it .020 over so had them side by side for comparison.
 
Will not get into an oil debate , as long as quicksilver 25 40 is fine than so am i
 
So you say there are better oils out there than Quicksilver. What credentials do you have that make you the expert in motor oils? I’m not trying to be critical I’m just curious. Quicksilver and Mercury are the only oils recommended by Mercruiser. I would think that would be the oil of choice. Especially considering Quicksilver oil is reasonably priced at Walmart.
Well, I operated heavy equipment and worked on it for years. I have seen what dino oil, synthetic blends and full synthetic look like coming out of an engine and Rotella T6 always looked the best. Mercury has a stake in their own oil and in Quicksilver, so it is no wonder why they recommend them. I used Quicksilver for the 6 years my warranty lasted. Then I switched to Rotella and the difference was obvious. YMMV. I am not an oil expert, to answer your question and not a chemist. I just slept in a Holiday Inn Express the night before I posted. Oh, and Rotella T6 is only $23/gallon at Walmart, which I find very reasonable.
 
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Who is "they"? Any decent Merc shop will have what you want in stock.

No, that's incorrect about the stern drive gear oil. Merc's Hi-Perf stuff is an excellent product.

Side note: Merc brand is the same as Quicksilver. Merc re-packages it to be sold at places other than Merc shops. "Merc" branding/packaging can be only be sold at a Merc shops.
While I have experience with engine oil (#maggieiscrazy I am not an expert nor do I have "credentials") I did not have experience with stern drive oil. I only use Merc High Performance with great success.
 
I use 15W40 Rotella T6. We don't boat in cold weather, so the cold viscosity isn't important.
I used that or the Chevron Dino in my 40 year old chris crafts. Worked well. With my newer mercs, I am going to stick with the recommended quicksilver at this point.
 
If you guys want to learn everything about oil and what you think is the best will surprise you go to or Google this blog and he has a list of the top 150 motor oils or 250 motor oils Henry how they compare and you will be very very surprised. Google Rat 540 blog and this guy knows oil
 
If you guys want to learn everything about oil and what you think is the best will surprise you go to or Google this blog and he has a list of the top 150 motor oils or 250 motor oils Henry how they compare and you will be very very surprised. Google Rat 540 blog and this guy knows oil
Don't forget Bob. https://bobistheoilguy.com/
 
This guy blows Bob away he attached to motor oil has like a hobby you have to read rat 540 blog it's a long article but it shows you the shear strength and sheer pressures of motor oil and you'd be very very surprised at this list of 250 oils
 

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