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oil recommendations

topgun

topgun

Well-known member
I know. Use the search button. I have and now I am more confused. I just want to know what some of you guys run. Or should I spend a lot more money for the mercury stuff. Can I use oil and filter that can be bought at advance auto. If so which oil and what filter and part number 91 5.7 mag....:o
 
Just buy the quicksilver 25w 40 in the gallon jugs and a quicksilver filter they have them at wallmart
 
Yeah, but the odd thing is i've been told through certain sources that "everyone" agrees on Amsoil diesel (even for gas engines) on Merc I/O's.
Now, It's a pretty decent source but I'm not seeing the online documentation. Even on other OCD sites.
But I'm not willing to discount what I was told... And.... I happen to swear by the Amsoil outboard oil I've used on my 225 Merc for years.
Folks- Opinions for me and Topgun on what you stick in a Mercruiser for an oil change?
 
Sim, Not my words but explained better then me about your "diesel".

Though called by many Diesel oil. The oils are properly called HDEO oils [Heavy Duty Engine Oils] which are made to perform in the most severe commercial operating conditions in diesel and gasoline engines . Those are the oil commercial maritime companies use in ther high speed diesel and gasoline engines it is the best choice of oil for your engine. "Real" Diesel oils have different additive etc.formulations than the HDEOs.
 
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Running Castrol GTX 10W40 and car filters in my 305 Chevy powered Glassmaster for 30 years and the motor hasn't missed a beat. I'm gonna stick with that.
 
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Valvoline vr1 straight 50 semi synthetic, considerably more oil pressure than anything I've ever run.
 
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My 454 has aftermarket oil filter set up that has 2 side by side oil filters mounted on the transome.....was that way when I bought it, turns out they are Ford FL-1A filters. I buy good filters....either k&N or Mobile ONE filters and I used to run Full synthetic 10W40 oil but its getting harder to find at the local Orileys/ napa/ wallymarts, so I've been running the 15-40 Rotella diesel oils the past few seasons.
 
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I use Mobile 1 full synthetic with Fram filter. The oil still looks brand new after a season but gets changed anyways. I have a remote filter so the part number would be different. I really think synth oil is overkill for most boats due to not getting much use in a season.
 
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i've been searching this same topic, still undecided on what i will use, but i pick the new boat up tomorrow so i need to decide soon. want to get it out asap.
 
I am not much of an I/O guy, but all of the guys around here that have "performance boats" have told me face to face that they use Amsoil 15w40 HD marine diesel. When I asked my Amsoil rep about it, he said it was the most popular oil that he sells for I/O boats. The thing that got me started asking people was that I was trying to sell some oil, but I had no luck because everyone I asked was already using it. I use Amsoil in everything I own, car, truck, boats, lawn mower, weed eaters and even my rc boats.
 
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Royal Purple strait 40 is what I use, but only because this is what the
previous owner said that's what he used since the rebuild which has 75hrs
on motor now. Im starting to reconsider this after reading a post that
Gimme Fuel had on here a couple weeks ago. It was the best info on the
oil topic I have seen ever for high perf engines. Cant remember the title
of the thread but it wasn't to long ago.
 
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For a small block, I would say straight 40 weight would be good. 50 is a little thick for an SBC unless you are running the royal piss out of it. Valvolene VR1 is great stuff in a marine engine for the money and surpasses many full synthetics with its film pressure ratings. It is available at most NAPA or similar chain stores. As far as filters go, most stores will carry an equivalent to what you are running now. NAPA gold are very good filters. Fram really are poorly built for the hype they receive. Stay away from the racing filters, they have a larger pore size to allow higher flow rates, but in return also allow larger sized debris to remain in the oil.
 
Personally, I think you guys are worrying too much about this. Run a quality name brand oil and filter (auto or marine type), change it as the manufacturer recommends, and change it at the end of the season just before storage and you can't go wrong. Remember, these are not built race motors running on the ragged edge at 6500+ rpm all day long. They're relatively mild engines with relatively low compression and turning well under 6000 with most of their time in the 3500 to 4000 range.

John
 
Thanks guys, That helps me finally decide. As far as the filter goes, I agree that napa has good filters but do I just ask for one for a 91 mercruiser? Probably not. So does some one have a number or an application. For example is it a ford 1a and so forth or is it a regular chevy sb filter.
 
atc250r said:
Personally, I think you guys are worrying too much about this. Run a quality name brand oil and filter (auto or marine type), change it as the manufacturer recommends, and change it at the end of the season just before storage and you can't go wrong. Remember, these are not built race motors running on the ragged edge at 6500+ rpm all day long. They're relatively mild engines with relatively low compression and turning well under 6000 with most of their time in the 3500 to 4000 range.

John
Click to expand...

100% in agreement here.....

Don't sweat this too much....

Whatever oil and filter you decide on, just keep them fresh.
As atc250 was sayin, unless your running a super high performance setup then just run a name brand oil and filter.

However, a couple of simple things to consider,

If the engine is a used engine and it never had a synthetic in it then stick with a conventional oil, but if it's brand new engine then a synthetic maybe a better choice.

Also, whatever you choose to use, it's kinda important to stick with that.

Myself, I'm a Vavolene guy, --- most of their oils have a pretty good rating in terms of viscosity breakdown.

But again, all the name brand oils are pretty darn good products these days --- Royal Purple / Vav / Quaker St / Mobile / etc... all good stuff for our engines.
 
If you can get a part number off the old filter they could probably cross reference it. My guess would be if it's a 91 5.7L one for say a 91 Chevy Caprice 5.7 would be the same.
 
topgun said:
not at all.:confused:
Click to expand...
nope....it's one of those deals where every person has a different idea and who really has oilling problems anyways??? mostly it's something else that is the failure. But whatever makes an individual feel good, thats what you should do. If you run a full synthetic it's gonna make you feel better, same as if you run a good higher quality/more expensive oil, it makes you feel better. If you run some cheap crap then that shows you don't really care one way or another. Just my $.02
 
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