Zinc additive for engine oil?

[DaveM]

I admit that I have been away for a while--layoff, relocation, blah, blah, blah and now it is time to get into the boating scene. While buying oil/fuel filters this marine mechanic started a rant about EPA standards and needing to use a zinc additive to the engine oil. Otherwise I will flatten the lobes on the engine cam. I have been using marine SAE30 for years. My question: do you think this guy is correct, or was he just trying to up-sell me on his synthetic motor oil?

-DaveM
1994 Wellcraft Excel 20SL
Volvo Penta V6 4.3 GL-SX

 

[Scott Danforth]

I'm running Rotella Diesel 15w-40 for the zinc content. I run it in everything with a flat tappet can from my boat to the truck the Audi.

Not trying to turn this into an oil thread, just providing my perspective

 

[DaveM]

Whoops, should have added this under Non-repair I/O and Inboards.

Thanks for the reply. I too was trying to carefully word this to avoid an oil preferences discussion and just stick to zinc additives in motor oil. Never knew that was a concern.

 

[gbeltran]

Your 94 should have roller lifters, and no need for any additive. Also, on an engine with some hours, as in broken in, and stock springs/cam, those don't pose much problem either.

 

[DaveM]

Good to know, thanks!
This local marine mechanic dude is so far not gaining my trust.

 

[HT32BSX115]

I have been using marine SAE30 for years.

And you haven't flattened them so far, right?

or was he just trying to up-sell me on his synthetic motor oil?

Well, if he is in fact, trying to sell you synthetic oil then, YES. I'd say he IS trying to "up-sell" you. If you leave the boat sitting in the water, you might consider using an NMMA FC-W oil of your "Brand" choosing, And you can buy it right here on iBoats (if you 'd like to support this forum etc)

"But truth be known" You can just keep doing what you've been "doing for 30 years".................You already have "experience" with that!!

Regards,


Rick

 

[WIMUSKY]

The mechanic is blowing smoke. Your motor is new enough where it doesn't need a zinc additive. And you surely wouldn't find enough zinc in synthetic oil. As mentioned, Rotella has a higher amount of zinc in it than most oils. But even then a guy should use ZDDP zinc additive "if" you had had a much older motor. Not only are we talking about cams, but also valve seats which weren't hardened. Even then, some guys changed to hardened seats so they wouldn't have to worry about zinc.

I'm not sure when they went to hardened seats. Sometime in the mid 70s? IDK I do know it wasn't the 60's. Basically, when unleaded gas was mandatory....

 

[Lou C]

Hardened valve seats came on line about 1972; compression ratios were also lowered to work with non lead gas.

 

[Lou C]

Why not look up the zinc level in the oil you are using; if it's around 1000 ppm you should be fine. I use the Merc 25/40 that also has more zinc than car based oil...

 

[HT32BSX115]

Hardened valve seats came on line about 1972; compression ratios were also lowered to work with non lead gas.

Ran unleaded gas in the 1965 Mercruiser for 40 odd years......ran it in my 1957 Ford 292 Y-block, ran it more than 100000 miles in a 1971 Ford LTD (429 V-8) ran it in many pre-1972 engines. Never ONCE hurt the valve seats in anything.

I am thinking that lead thing "saving" the valves is an old wives tale....... (my buddies that ran propane thought that too!!)


Cheers,


RIck

 

[WOEISMEIGOTTA470]

Pretty sure you already got your answer but figured I'd add my 2 cents. It's been my understanding that the zinc additive for oil, or special oil with higher amts. of zinc mixed in, are typically marketed as "break-in" oil. It's basically added insurance for when you start and run your brand new/rebuilt engine, and helps protect from wiping any cam lobes, esp. for flat tappets (basically excludes most all modern or non-high performance vehicles/engines which today commonly use hydraulic rollers or OHC's).
After the break-in period is over though, it should be plenty safe to use a standard motor oil of your choosing or whatever is recommended from the manufacturer. Break-in oil is just that, don't really see why you should continue using it after, just wasting $$$. FYI - I have an older freshly rebuilt 1968 GM 250 inline 6, it has hydraulic flat lifters and am currently running this stuff from comp cams to break it in...see link. My engine doesn't have hardened ex. seats, but that has nothing to do with the oil. For insurance for that I mix in "leaded fuel replacement additive" into the gas, but from what Rick just said from his experience, this too might also be unnecessary ("old wives tale").
BOTTOM LINE: Is your engine already broken in and running fine on the SAE 30? No need for the special stuff, stick with what you know.

 

[HT32BSX115]

BOTTOM LINE: Is your engine already broken in and running fine on the SAE 30? No need for the special stuff, stick with what you know.

Well....yup. My old 150 Mercruiser (Dad bought new in 1966) was ran with whatever oil we could buy. Generally straight SAE 30.

39 years. I sold it in 2005, It still ran, (albeit was a tad wimpy)

I'm sure it was pretty worn out but after 39 years, what do you expect? If I had kept the boat, I would have rebuilt the engine, put an SEI drive on the back and kept on running it!


The important part of breaking in a cam is well documented by Comp and others...... Using a good cam/follower lube on assembly and maybe their break-in oil is a great start.

After break-in.............You can probably run whatever you like and it'll go at least 39years!!! That'll cover most people............


Cheers,


Rick

 

[DaveM]

Thanks for the info! I did go with straight SAE 30W, just like I always have.

Not sure if this marine mechanic dude is continually up-selling or just being a know it all and taking me for a fool. Either way, the conversation always seems to turn into a disagreement and me walking out, without buying any parts or service.

 

[NHGuy]

I like zinc oils such as Quaker State Defy for flat tappets. Never ruined a cam, but the newer oils supposedly can allow contact on sliding surfaces. So I go the extra step.
Also I think it's maybe smart for my Baja since I put an added lift cam with uprated springs in there.
But I do agree, that guy was selling you something unneeded. Roller motors don't have sliding parts.