Engine Oil ???

[Nev'r Enuff]

I have a 1986 SeaRay 30 ft with twin 350's. I have been using Merc oil 25W40 for years and have had no problems. Is there a better oil to use on my 950 hour engines? I was told not to change to Synthetic at this stage? Thanks Randy..

 

[Bifflefan]

Re: Engine Oil ???

I was told not to change to Synthetic at this stage? Thanks Randy..

That sounds like a good oil to use.

The only time you should not use a synthetic is for the initial breakin. Other than that you can use it any time.

Im sure some one will have a different opinion about this tho...

 

[180shabah]

Re: Engine Oil ???

Just stick with what your running and enjoy.

 

[45Auto]

Re: Engine Oil ???

I have a 1986 SeaRay 30 ft with twin 350's. I have been using Merc oil 25W40 for years and have had no problems.

Imagine that!

You've been using what the manufacturer recommends for years with no problems, and now you're thinking about changing based on what someone you know NOTHING about recommends on some BS internet forum????

Good luck!

Truth is, your engines will most likely die because you didn't replace the manifolds and risers and sucked water into a cylinder, or you didn't replace the impellors and overheated them, or you didn't winterize them correctly and cracked the block. Oil type (as long as you follow the manufacturer's recommendations and change intervals) should be the least of your worries.

 

[concordsteve]

Re: Engine Oil ???

I have a 81 305 merc and I also want to switch to synthetic because it is known to be a better oil. My manual says to use sae30 under 90 degrees and sae40 90 or above do you guys think think 10w 40 would be a good choice. I don't recall seing straight weight synthetic oils on the shelf but I may be wrong.

 

[Nev'r Enuff]

Re: Engine Oil ???

Imagine that!

You've been using what the manufacturer recommends for years with no problems, and now you're thinking about changing based on what someone you know NOTHING about recommends on some BS internet forum????

Good luck!

Truth is, your engines will most likely die because you didn't replace the manifolds and risers and sucked water into a cylinder, or you didn't replace the impellors and overheated them, or you didn't winterize them correctly and cracked the block. Oil type (as long as you follow the manufacturer's recommendations and change intervals) should be the least of your worries.

Yes I will keep the suggested oil in the future. Thanks for all the help.

 

[rbh]

Re: Engine Oil ???

The engines in our boat are 1985 merc 260s, the mfg sticker recomends straight sae 30 wt, (but we have been using the 25-40 merc oil).
sae 30 wt is what we run in generators and anything that runs long and under load for long periods, 10w30, 15w40 would not hold up as good.
rob

 

[45Auto]

Re: Engine Oil ???

Latest Mercruiser fuel and oil recommendations:

http://www.mercurymarine.com/serviceandwarranty/mercruiserfaqs/fueloil.php

Oil chart from above link:

The reason they SPECIFICALLY DO NOT recommend the multi-viscosity automotive oils (see the NOTE just below #5) is because they are formulated from the thinnest base with plasticisers added to give the higher weight when hot. For example a 10W-40 is a 10 weight base oil.

As you shear enough of the plastic molecules under load, the oil slowly reverts to it's base weight. A heavily loaded marine engine becomes very unhappy when you start running thin oil in it .......

Nev'r Enuff, just as a sidenote, I also have a 1986 Searay 300 with twin 350's. I recently had to replace a single piston in the starboard engine because of detonation damage. Engine has about 650 hours on it, had 150 PSI in all other cylinders. Internally it looked brand new. Bearings and cylinders looked new, no wear rings at all at the top of the cylinders. Replaced the bad piston with a new standard piston and it runs like new. i have all the receipts from the marina where it was maintained by the 2 previous owners, it's had the factory Mercury oil in it since new, changed every year.

 

[Apollo75]

Re: Engine Oil ???

I have a 1986 SeaRay 30 ft with twin 350's. I have been using Merc oil 25W40 for years and have had no problems. Is there a better oil to use on my 950 hour engines? I was told not to change to Synthetic at this stage? Thanks Randy..

Please consider this information from the following article :

"Instead of making motor oil with the conventional petroleum base, "true" synthetic oil base stocks are artificially synthesized. Synthetic oils are derived from either Group III mineral base oils, Group IV, or Group V non-mineral bases. True synthetics include classes of lubricants like synthetic esters as well as "others" like GTL (Methane Gas-to-Liquid) (Group V) and polyalpha-olefins (Group IV). Higher purity and therefore better property control theoretically means synthetic oil has good mechanical properties at extremes of high and low temperatures. The molecules are made large and "soft" enough to retain good viscosity at higher temperatures, yet branched molecular structures interfere with solidification and therefore allow flow at lower temperatures. Thus, although the viscosity still decreases as temperature increases, these synthetic motor oils have a much improved viscosity index over the traditional petroleum base. Their specially designed properties allow a wider temperature range at higher and lower temperatures and often include a lower pour point. With their improved viscosity index, true synthetic oils need little or no viscosity index improvers, which are the oil components most vulnerable to thermal and mechanical degradation as the oil ages, and thus they do not degrade as quickly as traditional motor oils."

This and much more can be found here :

http://en.wikipedia.org/wiki/Engine_oil


Enjoy

OFM

 

[Snowfish]

Re: Engine Oil ???

Interesting stuff here. I've been running Resolute 20w50 Racing Oil for quite some time now. After digesting this and other links I'm starting to think Straight Weight 30 or 40 would give the best protection.

 

[concordsteve]

Re: Engine Oil ???

interesting information does the mercruser quicksilver synthetic have a weight rating ?

 

[joncrisler]

Re: Engine Oil ???

Interesting stuff here. I've been running Resolute 20w50 Racing Oil for quite some time now. After digesting this and other links I'm starting to think Straight Weight 30 or 40 would give the best protection.

You should NOT be running a racing oil in an engine that goes long hours between changes. Racing oils either have little or totally omit some additives like detergents (and other things) but add more of other ingredients. Unless you are changing the oil every few months and only put 25 hours on the engine, you should use someting else.

Now, there are some oils label "racing" that do not fit the above formula, but most do. You should switch to some other 20w-50. And I am a firm believer that straight 30 or 40 weight old is old school.

The Merc Quicksilver Synthetic Blend is a 25w-40 as well.
http://www.mercurypartsexpress.com/us/synthetic-blend-mercruiser-engine-oil-946-ml-32-fl-oz-p85.html

 

[83Evinrude]

Re: Engine Oil ???

I've been trying to decide what oil to use for the first oil change in my Volvo 5.0GL as well.
The 30W synthetic the owners manual calls for, doesn't have good availability in my area due to all the boat shops going under. The original owner used 30W Valvoline dino oil.

I have been thinking about these, all available at Walmart locally:

Quicksilver 25W-40 - Silver Jug (I don't think this is the synthetic blend)
Castrol - 20W-50 - (Dino)
Shell Rotella or Delo 400 15W-40 - (Dino)

I can also get Mobil-1 15W-50 Synthetic at Orielly Auto

I know any of these should work, I would just like the best for the money.

Does anyone know what Oil and Filters Don S and Bond-o use?
Perhaps they will fill us in.

 

[Utahboatnut]

Re: Engine Oil ???

To the OP I think I would use what got you to 950 hrs. That seems to tell you everything you need to know. Kind of the "go with what brung ya" mentality.

 

[Knightgang]

Re: Engine Oil ???

My only comments about synthetics are that they its molecules are more similarly sized then conventional oil. Therefore, it does not break down as quickly and can withstand more extremes before causing problems. Hence the reason they were orginally created to be used in jet engines. So before anyone dcides to switch to synthetic, let me ask these questions...

Do you plan on running prolonged oil change intervalls?
Do you use your engine under extreme operating conditions above what it was designed for on a regulat basis?
Do you have a problem with sludge buildup in your engine?

There are more, but if you answered no to all of these questions, you do not need synthetic, and I would stay with the MFG recommendation...

 

[backwater dawg]

Re: Engine Oil ???

I have a 1988 Merc 5.7 that I bought new---the first summer I owned the boat, at my birthday bash my freind and boat salesman brought me a case of merc 25-40 oil and said " ALWAYS USE THIS OIL " ---2500 hrs later the engine runs perfect---forget all the fancy s**t and use what Merc says and it'll run a long time----good luck---Steve

 

[Dave1251]

Re: Engine Oil ???

83Evinrude;2364594]I've been trying to decide what oil to use for the first oil change in my Volvo 5.0GL as well.
The 30W synthetic the owners manual calls for, doesn't have good availability in my area due to all the boat shops going under. The original owner used 30W Valvoline dino oil.

I have been thinking about these, all available at Walmart locally:

Quicksilver 25W-40 - Silver Jug (I don't think this is the synthetic blend)
Castrol - 20W-50 - (Dino)
Shell Rotella or Delo 400 15W-40 - (Dino)

In 2003 Volvo went for dino SAE 30W to synthetic SAE 30W. They also change from 100 hours/annually to 200 hours/every 24 months between changes. From the above list, I would use quicksilver 25w-40 changed annually. That give you an oil designed for the load ranges found in marine use.