Help with best oil to use

[lifespan]

Sorry if posted elsewhere. I have a 1999 Maxum 2100 SC, 5.0 Mercruiser. So many opinions. What should I use in terms of brand, weight, synthetic etc?

[mmwjr]

I use quicksilver 25W40 per mercs recommendations

[lifespan]

Thanks Mike. You always give me good advice.

[lifespan]

Off topic, any ideas why one exhaust manifold might run hotter than the other?

[mmwjr]

How much hotter are you talking?

From what I have seen one tends to be 5-10 degrees warmed I guess it has to do with the t-stat house that distributes the water to them.

[Kevlar7r]

If one manifold is hotter than the other, there is good bet your manifolds are becoming corroded and not flowing enough water.



I would recommend breaking down the manifolds and risers and doing an inspection. Depending on what you see, clean or replace.

[lifespan]

What will determine difference between and cleaning and replacement? What is a cost to expect for parts?

[Kevlar7r]

Rather than taking this thread too far off topic, there are tooonnns of great resources on the internet that describe how to inspect manifolds, and what to look for.



As far as cost, if you do it yourself, $300-$1000 per motor, depending on what types of manifolds you have (wet vs. Dry joint) and what type you choose to replace with (ceramic coated). Labor really shouldn't be toooo much considering I can do both sides of a motor in an hour and a half including plenty of beer breaks.



Don't ignore it though. I've lost an engine to failed manifolds. Previous owner of my boat lost one as well.

[lifespan]

I appreciate it. I will admit that this area of maintenance did not cross my mind. Always learning. I am assuming wet joint given year, but will look at rider to determine. Facing engine, left was running hotter. Noticeable difference, but have not done a specific temp reading on either side.

Have my boat guy coming tonight to drain old gas and do fuel filter and water separator. Will see about pulling those and inspecting.

[Kevlar7r]

Back on topic for this thread, I've been using Rotella T 15w40 for a number of years now. It is a heavy duty diesel oil, with a lot more additives to reduce wear. It also simplifies things around my place as I run the same oil in my Cummins diesel truck, my tractor, and my off road 4x4. They sell it in 6 gallon cases at sam's club.

[Phillbo]

Delo 400 Diesel Oil in mine.

[Kevlar7r]

Glad to hear I'm not the only one running diesel oil.

[mmwjr]

Originally Posted by Kevlar7r

Glad to hear I'm not the only one running diesel oil.

yea but with Phillbo selling his boat its back to just you

[Kevlar7r]

Well, with all the engine trouble I've had the last few years, I'm not going to go bragging.... But none of those problems have been oil related.

[Phillbo]

I've run Diesel oil in all my boats and never an oil related issue. It has better shearing capacities.