Hey Guys:

I have a 2005 525EFI and have 19 hours on the engine. Getting ready for the proverbial oil change. I realize there are other posts but I'm getting too confused, so I thought I'd ask a simple question.

Do I stick with Merc's oil or do I go to Mobil 1 15w-50? I called Merc and all they said was that their blend works and they have no reason or time to test other oils, however, if I had an engine failure and it was a result of an oil not of their viscosity, I could possibly void my warranty. What do you guys think?

Ron

merc racing sells M1 off the race truck and there at x-site....we use royal purple (RACING 41) and have had amazing results with it...even when the engine filled with water at wot... i have no idea about warranties...ya get NONE when you race.

Ron, synthetic oils are superior in every way shape and from over conventional,, except PRICE, why not use the very best for your baby,, Merc. sells their 25-40 conventional for 3 bucks a quart, you can get M1 for approx 4.00 at walmart. They are certainly not going to reccomend anything but their own stuff they sell..

I have a pair of 525EFI's and have been running MOBIL 1 (0W to 40W) black tops, without any problems for 2 seasons, approx 170 hours.

M1 15W50 in my 500EFI past 3 seasons, and M1 15w50 in 60 hours on my 496HOs so far this season. Most I know swear by it.

-PAO derived synthetic oils lubricate better than anything out there.

-The additive package in an oil is as critical as the oil itself.

-Using the proper viscosity is based on the engine's set-up and environmental factors and knowing a synthetic's "pumping characteristics" is key in determining it when transposing to a synthetic's "weight" from a conventional oil's recommendations.

-A good flowing and trapping oil filter is essential to long bearing life.

-Proper oil change intervals ought be determined by your driving habits.

-These are all undisputable facts.

FYI

I personally would NOT use a 0W-40 in an HP 525 EFI HP unless running it in Alaskan waters.

I would use:


15W-50 Mobil-1

20W-50 Mobil-1 V-Twin

Redline 15W-50 or 20W-50

Mercury 25W-40

A premium 30 or 40wt like Kendall

Kendall 20W-50 Racing

Rotella 15W-40

Royal Purple 20w-50

Maybe Mobil-1 Motorcycle 10W-40 ?

I am editing this: After reading Bob's recent tests and analysis of Amsoil products which appears in my Mobil-1 V-Twin thread I am no longer going to use Amsoil. He found it's additives were short-lived and highly reactive to metals. I am sticking now with only Mobil-1 and Redline synthetic products.

Just my personal feelings based on my readings is all. A 0W-40 has a ton of polymers in it that don't respond to it's higher weight until the molecules uncoil at high temps. Until then you have a very thin oil in a relatively large toleranced engine. When a manufacturer says 25W-40 and you go to "0" W oil you are basically on your own. It may be good but you won't know till you do a tear down. I tried 0W-30 synthetic in my lawn tractor and it vibrated badly. I immediately drained out $ 16.00 of oil and pitched it and put in MObil-1 V-Twin and the vibration decreased 80%. You may not "feel" vibration but if it is there it is not a good thing. Viscosity at moderate temp is cruicial as are cst's at higher temps. The "0"W's were developed for European car manufacturer's to meet CAFE regulations and they built the engines's around that weight synthetic oil and many of these vehicles have sophisticated dry-sump systems.

It's your call.

Thanks Guys:

I really appreciate the input