mercruiser 25/40

[tobo57]

I have a late model mercruiser,350 with 315 mpi chev. engine. I would like to get away from their oil and i yr. oil change recomendation.
Would 20/50 castrol or rotella15/40 with a ac filter and twice a year oci be a good move?

 

[BUBBA0420]

tobo: Check out my post on Mercruiser Oil
Replacement. I too am not fond of the Merc
Oil and I am going with either Straight 30W
Delo 400 or Havoline

 

[tobo57]

merc. says to run a 40 wt.if not a multi. would be a poorer choice.Not to run a syn.
I am concerned about a deisel oil in my gas engine, butt a 15/ 40 would be my ist choice

 

[BUBBA0420]

Well Delo 400 makes a 15/40. My Merc Manual
specifies a straight 30 Weight.

 

[Ryan00TJ]

Just make sure the Diesel oil is dual rated for BOTH gas & diesel and you'll be fine. Oil's like Delo 15W-40, Delvac 15W-40 etc all have stronger additive packages than your off the shelf Castrol 10W-40.

Does your manual actually say to not run synthetic? I can't for the life of me imagine why!!! Marine engines are some of the hardest used in the world and IMO Synthetic should be a must.

Good Conventional 15W-40's

Delo 400 15W-40
Delvac 1300s 15W-40
Rotella 15W-40

Good Synthetic's

Schaeffer 15W-40 PAO Blend
Amsoil 10W-40 Marine - More like a straight 40w
Amosil 15W-40 HDD & Marine
Redline 15W-40 HD Diesel
Mobil 1 5W-40 Delvac 1 & T&SUV

 

[tobo57]

Mercruiser matinance manual for 03 states,THE USE OF MULTI-VIS. OILS [OTHER THEN MERCRUISER 25/40 OR A GOOD QUILITY 20/40 OR 20/50]SYN. OILS OR OILS THAT CONTAIN SOLID ADDITIVES ARE SPECIFICALLY NOT RECOMENDED.

 

[tobo57]

narrowed it down to castrol 15/40 syntec-blend[4x4] or rotella 15/40,with twice a year oil changes. Or mobile 1 15/40 changed once a year.Is LLpensoil 15/40 same as their deisel oil?
thoughts plese

 

[JonS]

I've always used straight 30 Delo 400, and this year i've switched to Delo 15w-40 in my V-8 inboard. I like it alot. I chose Chevron Delo 400 15w-40 over the Rotella because of the iso-syn and that it has less ash (1.35 vs 1.47) over the Rotella. Otherwise i've heard good things about Rotella.

 

[JimG]

Just curious, why don't you like the Merc oil? Check out the UOA I posted on my friend's HP525's. It's a pretty strong package. I'm thinking about switching from the Kendall I'm using to Merc 25/40 based on this report...

 

[tobo57]

I just think there is a better oil out there thats easy to find and costs half as much.I would like to go to twice a year service instead of once as merc. recomends.

 

[JimG]

I do twenty hour oil changes on the 509 (T-Bred), 30 hours on the 351W (Donzi). That's about four times a year on the Thoroughbred and 3 times a year on the Donzi.

I've been running Kendall 20w50 based on Mercruiser's recommendation on their 600sci, 850sci and 1075sci. Been performing pretty good, but specs not as good as the Merc oil (I get Kendall for $2.10 per quart vs Merc for $2.33 per quart, btw)

Jim

 

[BUBBA0420]

Well Tobo I am going with the DELO 400
straight 40W. The Merc oil thins out in my
engines even when only cruising at 3000 RPM

 

[tobo57]

i am switching to Delo 400 15/40.Bub,With your problem of low oil pressure and the amount of hrs. on your engines I would lean to the 40 myself.Went to WM today they have Mercruiser 25/40 at 3.95 a qt.I don't see it.
Thanks for the help, guys

 

[JimG]

Good choice on the Delo 400. I recently bought 22 gallons of new Delo 40wt from a guy who repowered his 46' Post sportfish. His new engines require 15/40 so he sold me the whole shebang for fifty bucks! So you know what I'll be using!

Yeah, Walmart down here jacked the price of the Merc oil to $3.95 also. WAY too much! We have Academy stores down here that sell it for $2.33 per quart.

 

[stingray69]

I always thouight the reason to stay away from synthetics was because of possible water contamination/condensation. They claim their Merc oil can take some water and still be okay. If you have a built motor or are an anal motor guy, then synthetics should be fine for you, but not for Mr. Procrastinate.

 

[BUBBA0420]

Stingray69: Merc now makes a Semi Synthetic Oil
Delo 400 that we are referring to is NOT a
synthetic. Delo is a Diesel and gas rated
Heavy Duty Engine Oil and it sure quiets down
an engine compared to the Merc Stuff

 

[KBFXDLI]

I have found the Merc oil at West Marine for $11/gallon which aint bad. Plus all my Blackstone tests give good numbers for the anti-corrosives on my 380hp 7.4l horizons.