Opinions on Zinc additives for older engines

[jbousman88]

What is everyone's opinion on engine oil in the older 350 and big block engines? Full synthetic, conventional? is zinc additives necessary?

[jbousman88]

This always seems to come up on here so here is a little info a friend sent me if anyone wants to read:

https://www.mastercraft.com/teamtalk/showthread.php?t=47267&page=2

http://www.enginebuildermag.com/2014/08/preventing-flat-tappet-cam-failures/

[michael hunter]

I was told by Mobil the Mobil 1 15w50 is the oil they recommend for all marine engines old or new. I have been useing Mobil 1 in my cars since 1977 when it first came out. All of my boats use Mobil 1 . In the past 28 years I have never had any oil related problems.

[Zkdk3000]

Just changed oil in my 92 Comp with zr1 5w-30. One of the highest zinc levels.


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[jbousman88]

ZR1 or Valvoline VR1?

[NorCalPR]

Just changed oil in my 92 Comp with zr1 5w-30. One of the highest zinc levels.


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Thats a very thin oil for any boat motor. Dont focus on one thing And leave out the rest ;)



Rotella dino here. Delo is also another good one to run. Nice thing is theyre cheap at Walmart

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[Zkdk3000]

ZR1 or Valvoline VR1?

Sorry that was a typo, vr1.


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[Zkdk3000]

Thats a very thin oil for any boat motor. Dont focus on one thing And leave out the rest ;)



Rotella dino here. Delo is also another good one to run. Nice thing is theyre cheap at Walmart

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What're you recommending then? I haven't had any issues thus far.


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[NorCalPR]

What're you recommending then? I haven't had any issues thus far.


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What every boat manuf recommends...

A thick oil, 15w40 or thicker like a 20w50. But since its easier and cheaper to find, rotella 15w40, mobil1 15w40.......

Reason being a boat engine sees much more load, heat, and high rpms for a longer period of time than a car engine. So while a chevy 350 block in a truck may use a 5w30 or a 10w30 just fine, its just not enough for a boat because of the conditions.

If youre only riding in the winter time i suppose it would be ok, but other than that, id never run that thin of a oil in my boat...

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[Zkdk3000]

What every boat manuf recommends...

A thick oil, 15w40 or thicker like a 20w50. But since its easier and cheaper to find, rotella 15w40, mobil1 15w40.......

Reason being a boat engine sees much more load, heat, and high rpms for a longer period of time than a car engine. So while a chevy 350 block in a truck may use a 5w30 or a 10w30 just fine, its just not enough for a boat because of the conditions.

If youre only riding in the winter time i suppose it would be ok, but other than that, id never run that thin of a oil in my boat...

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It's a 20w-50, I didn't even realize I had stated 5w-30. One beer too many last night..


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[cadunkle]

Zinc and phosphorus requirements are directly related to valve spring pressure and cam ramp rate. Marine engines have low lift, slow ramps and soft valve springs, and do not turn high RPM. There's no need to run an additive except for cam breakin or if you are running an aggressive cam (ramp rates, not duration) and strong valve springs.

Personally I use Rotella T6 in the 454 in my boat. I get it in 2.5gal jugs for my truck and it's easier to just get one oil that works well for everything in the fleet and is a reasonable price. zinc/phos levels are a bit higher in T6 than in typical oil today but not what they were in proper oil a decade ago. It's good enough for my engines, even the 460 with a fairly rampy cam and stiff springs.

[zroe]

I found Lucas Oil Hot Rod and Classic oil on Amazon. I used 10w-40 but they have 10w-30 and 20w-50 as well.


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