There's what, 2400 Members on here? You're likely to get close to that in opinions.

There's many on here that swear by Amsoil, Many more by VR-1 (Off road racing stuff only, particularly if you're running hydraulic or mechanical flat tappets), and a handful of us that I know of that are running the Joe Gibbs stuff. The reason for this stuff is make SURE you're running oils with high zinc content, and I don't care if you're running flat tappets or a full roller motor, run high zinc! The zinc is removed from street oils for emiisions reasons only!!!!

Your choice onto brand, but honestly, I'd run lower viscosity than 20w50, more like the 10w30 or lower if running VR1.

And heres why on a jet boat. This is gonna get long, and I'm sorry and famous for that. Gord and I had an even LONGER conversation about this awhile ago.

Jet boats do NOT see water or oil temps anywhere near street use temps. 160-180 is pretty much on the high side for most of us as far as water temps, my boats don't seem to break the 140 mark usually (Hot/cold out, don't seem to matter, that's the water temp they read). Oil temp I've never measured (Moo will), but Marcsrollin tells me all of his oil temps have been about 50 degrees above that. I'll take his word. Why this is important, and part of the reason why looser clearances are required on marine engines is, that Viscosity is actually a measurement of resistance to a major extent.

The number Before the W is the cold operating temp viscosity and the number after, the "hot" ,or running temp, viscosity. Generally, the broader the range the better, but in our case a little bit different. I've run both Moo and Pickle in both 115* plus weather and 65* minus weather. Water temps VERY reflective of the ambient temps, and oil pressures and water temps remain pretty much constant no matter what. Much like a car engine, where the op temps SHOULD remain somewhat the same in winter and summer if the cooling system and thermostat are in good condition. That's why the 5w30 and 10w30 in extreme swing climates for cold starting and warm-up.

On a jet boat, I am hard pressed to understanding why anyone would run higher cold viscosity oils (The number before the W) or even "gasp" straight weight oils (I've actually been recommended this), like VR1-50. The oil pressure WILL grow, granted, but lets be honest, what is considered adequate oil pressure? If I run normally 45 PSI, given a good solid oil pump, I can easily hit 75 PSI simply by changing the oil involved. Something to think about when buying a craigslist boat. Again, Oil pressure is RESISTANCE in the system. There's too low oil pressure, and there's way too high, IMHO. 

Personally, I run 10w30 Joe Gibbs Hot Rod oil. I wish they made a 5w30 or even a 5w20 synthetic, myself, because it is my firm beleif that my boats maintain 65-80 PSI oil pressure due to operating temp, and are not coming anywhere even near to close to the 30W limit of it. Lower viscosity, and slightly lower pressures mean the proper oil is not only getting where it needs to go, but is cycling through the system, and the twin filters, much more often. AND putting less stress on the timing set and oil pump and shaft in the process.

I'll wait for one or more of the engine guru's to chime in with better info or clarity. My info is from my one on one interaction with Pennzoil and Quaker State lab techs I had regularly back in the 80's. BUT, I will state this. I think 50 or so PSI is a target at operating temp on a fresh engine with a lower viscosity oil and a high volume oil pump, regardless of brand or application.

Ray

Search it on the web.

http://shop.joegibbsracingoil.com/cat-34-1-16/Hot%20Rod%20Oil.htm

Shipping is nothing. Use their Break-in Oil first on a fresh motor though, JMO. I still order it on the web, even though Farmergord gets it shipped to him from a local PHX speed shop (That does NOT stock it for me........ ) and Marcsrollin is keepin it all to himself at his shop in El Cajon........J/K Marc!.........yes, Rotella diesel oil is used a LOT in breaking in engines. In point of fact, its what my diesel pickup uses day to day. Diesels are NOT Hot Rod engines, however.   

Older motor though, honestly, isn't going to benefit much from the buck or better a case. Save the money for a future build or rebuild and use the lowest viscosity VR1 Off Road or Racing traditional. I think you'll be fine and Auto-Zone sells it. Don't want to put the engine into shock, and honestly, I think synthetics results are best realized when run from a fresh motor. Mixing the two can be very bad.

Straight weight oil, in ANY FORM of racing today is a VERY bad idea. I was told the Nascar boys do this recently. It would SHOCK me if true. Refer to the previous post or PM me as to why if it's not apparent. Straight weight oil is ONLY for Generators, compressors, and older farm/construction equipment that operate at the SAME controlled temp and RPM for many many hours at a time......

Ray

the weight oil i run is relitive to the bearing clearance that i run, larger clearance thicker oil. the crank and rods dont ever touch the bearings so the oil is all you got.

if you dont think that your oil temps match whats in your car, just wait till you put a temp sensor in your pan. i had to switch to synthetic oil because my temps were getting to the 250 range.

That's kindof the info I been looking for Ralph!  as I said, No oil temp sensors on my boats in the past.  Working off what I been told.

BUT, and I'm asking, you're a mentor to me, is this in the "family boat"? I seem to remember we had a conversation about water temps one weekend as well, and it would amaze me you were seeing those kindof oil temps when your water temp was nowhere near what Moo's was. Would shock me that oil temps exceeded 50% of what water temps read though. 

What viscosity were you running? first of all? and what?

And second, and I guess my point in all this, which is late  getting to it, is that pressure is important, to force the oil to the oil orifices, travels and galleys, etc instead of the path of least resistance. The balance is control of where it goes. or some semblence of control of where it goes. THAT relates directly to oil temp and viscosity.

You did well illustrate why Moo's first engine failed though, in the clearance end of it, I learned more than something from you about that!   

Ray

There's what, 2400 Members on here? You're likely to get close to that in opinions.

X2400  

I could not ever give a recommendation based on the limited information on you setup...

ok you are confusing me now ray.. are you telling me to run the 20w50? or to go with the 10w30?

Yes

GT

yes to both or what?  

The reason I said "yes" is because both "could" be right. If your internal clearances are "OEM" I would run something in the neighborhood of a 30wt, if it has been built "loose", then I would be looking into something in the 50wt range.

You may consider it a wise move to go with a 10-40 to split the difference. Most automotive machine shops build engines with OEM type clearances, which IMHO are tight for a jet boat application....Mainly do to the temperature fluctuations and RPM, but there are other factors involved.

Whatever oil you choose, try to stick to something similar. I never recommend going synthetic unless your going to stay on it for the life of the engine. Just a little thing I hate to see, the benefits of synthetic can't be realized if your are not consistent with the type of oil.

BTW, too much oil pressure is almost as bad as too little, many will disagree with me and that is OK, but what good can hitting the bypass in the pump and cavitating and foaming the oil? IMO, None...Foam is hard to pump and leads to heat issues, so try to stay below 80 psi at WFO.

Wish I could recommend an all in one oil...

GT

Ray, what purpose does high zinc oil serve in a roller cam motor?

Ray, what purpose does high zinc oil serve in a roller cam motor?

Missed the tail end of this due to work.

Glenn is right on the "depends" part, the synthetic part (Synthetics are great! But need to be run from the word go really, regardless of what the oil manufacturer says), and more info needed part. First thing to know is what the oil pressure ran before the change, but you prolly don't know that.

I'd think you're safer with a 10w30 than a heavier oil myself, and see what pressures build. If it turns out low oil pressure, particularly at temp, then maybe a heavier oil should be considered (Worn or really loose engine). Ralph and Glenn both pointed out oil temp, which is another important factor that I only have direct info from, well now 2, people. Moo's getting an oil temp guage and cooler only because engine oil will be routed through the blower gears as well. With 12 quarts in the thing, I don't forsee an issue with oil temps, but I'm overly cautious with what that boat is about to become.

Main reason I'd run high zinc oils even in a full roller motor is twofold. The zinc Di-whatever it is, has a plating effect on less than perfect or galled surfaces and even pitted surfaces, for one, adding also to rust prevention (It is the primary ingredient to galvanizing) from short to long term storage which all of our boats are victim. Second, it also has a cushioning effect on mating parts adding durability to lifter/cam interfaces and many more. It can't hurt, so why not?

I'm not saying run out and spend $120 a case for oil. VR1 racing oil is cheap, really, given all that we put these jet boats through, and tend to run them from 4000-5000 rpm 90% of the time, their cooling system, etc, etc, your initial question becomes far less "matter of fact" than you think.

Ray

It is hard to find good oil, so i just picked up some valovine sythenic 10w30s and will see what my pressure stands at.. but first I need to tune the carb, and timing since I installed an new high rise air flow intake and adding scoop on the hood.

it was not every time out..lol.. thanks for heads up, I would have gone for lucas too, but no auto stores here stocks them other than the stablizer thin, and 2 or 4 cycle motorcycle oils only.

Missed the tail end of this due to work.

Glenn is right on the "depends" part,

yep

Synthetics are great! But need to be run from the word go really, regardless of what the oil manufacturer says

Why? 

I'd think you're safer with a 10w30 than a heavier oil myself, and see what pressures build. If it turns out low oil pressure, particularly at temp, then maybe a heavier oil should be considered (Worn or really loose engine). Ralph and Glenn both pointed out oil temp, which is another important factor that I only have direct info from, well now 2, people. Moo's getting an oil temp guage and cooler only because engine oil will be routed through the blower gears as well. With 12 quarts in the thing, I don't forsee an issue with oil temps, but I'm overly cautious with what that boat is about to become.

12 quarts can heat up in a hurry. 

Main reason I'd run high zinc oils even in a full roller motor is twofold. The zinc Di-whatever it is, has a plating effect on less than perfect or galled surfaces and even pitted surfaces

Most who have the brains to inqure about oil will not assemble an engine with less than perfect, galled, or pitted surfaces....and if they did, all the zinc in the world won't save em.  It does, however, reduce friction in proper doses.

Yes, there is such a thing as too much zinc....

Yes, there is such a thing as too much zinc....

Absolutely!

Hell, here's "proof"   

I don't like fruit loops.  I'm a Lucky Charms Man, but not because of the rainbow on the box.

I just like to see all the information and facts to support statements.  That's all.  Statements without support are opinions...which are fine, but not for a technical discussion about oil.  I've done quite a bit of research, but I'm by no means an expert.  Everyone has their "thoughts", I'm just trying to see which ones hold water.

Yeah, I know...I'm just whippin' your skippy.... 

I'm a Boo Berry man myself...

GT