What do you use for engine oil on 454?

Just asking.. I have always had my boat serviced at the Sea Ray dealer and he has always used Merc. oil. Is there any reason you guys are not using this or does it matter? I always thought that merc. oil was formulated to work in the marine enviroment?
 
I used the Merc 20w40 oil religiously until I had it tested at the end of the season and saw it sheared to a 20 wt oil after 50 hours in a 2007 350 mag, easy use. Never again for me.
lots of good choices mentioned, but temperature range that you will use your boat in is critical to select the better choice. Straight weight oils might be fine, 15w40 oils from any major player could be fine, Amsoil, Royal Purple Marine, etc all could be fine. What is the ambient temps and how do you use/ run your engine?
 
Here's what I know about Merc oil. I'm positive that they don't own any refineries.......but I know Shell does!
 
Out side of my first boat (outboard), all my boats have been I/O until I bought this one. I always used straight 30 weight. On one of my boats, when I tired 10-30 once the boat warmed up, the oil pressure was low at idle, I went back to straight 30. The boating season around here the water on the river is about 50 degrees when we start, during the summer may hit 75-80 except when you head out to the ocean, it might reach 70 for a couple of weeks.
 
A 30, 0w30,5w30, and 10w30 are all the same viscosity when the engine is at operating temperature. They are different viscosities when cold, and slightly different along the way to warm. They use viscosity improvers to do this, and those are what can provide the problems in severe use applications. The VII's are polymer based, and can shear apart making the oil thinner at operating temperature. That is likely what happened to the 10w30 you used. Now, if you could if find a perfectly sheer stable 0w30 or 0w40, those would be ideal. In the practical world, you likely won't find those, so you want the best alternative. I would think early and late season air temps in CT are in the 50's, which would be hard for a 40 wt oil to work well, and even pushing a 30 wt. Until the engine and oil warmed up sufficiently to flow, you risk not having sufficient lubrication in some of the upper passages. That is why a multiweight oil is recommended now days (xxWxx). if you have had good results over the years with a straight weight oil, why change - ain't broke don't fix... But, many would recommend a multiweight oil, likely a 15w40 dual rated oil ( gas, diesel) like Rotella, Delo, Delvac, etc. As i mentioned, the supposedly shear resistant Merc oil sheared down 2 grades with limited use in my boat, so I would not recommend it based on that.
 
Like 390x says, I wonder who DOES make Mercury oil... We know THEY don't. Maybe they just shop the least expensive provider (the big guys) each season, or, on the other hand, maybe they require a certain ratio of this to that in a custom oil blend they then market as Mercruiser. Does anyone know?
Then at least we could compare better to, let's say, Rotella...

(regardless of single vs multiweight)
 
According to Merc mechanic in my marina that have been through the training on the subject, Merc oils have additives that are supposed to be friendlier to the engine that runs at higher rpms and help protect against internal corrosion. That doesn't mean other oils don't have that. Ultimately use a spec'd oil and change it as recommended or earlier.
 
Last edited:
I use Valvoline 30W and I add a can of lucas zinc oil additive. The newer oils manufactured today are for engines with roller cams and they have less zinc content than in the past. I lost a lifter and cam lobe and firmly believe it was because of the lack of zinc in the oil I had been using. Just my 2 cents worth. There are quite a few articles on the internet relating to this subject......
 
You must log in or register to reply here.

Forum statistics

Threads
113,352
Messages
1,430,967
Members
61,202
Latest member
p_griesman85
Back
Top