ZINC OIL ADDITIVE for older engines

redgoat · Jun 17, 2011

I recently learned that the current motor oils, namely SL and SM, do not contain the bearing protective property zinc plus phosphorus. Without this additive in the motor oil, older car engines could potentially be damaged. I would think my 44 year old Mercruiser 153 cu.in., 120 hp, 4cyl Chevy engine could be at risk. Should I add this zinc additive to my current 30W oil? I found some available on EBAY called ZDDP. If so, how much should I add for an engine with a 3 1/2 quart crankcase capacity? I would think all older boat owners should be alerted about this development in motor oil. I already add a lead substitute to my fuel system since current gasolines no longer contain lead.

mkast · Jun 17, 2011

Re: ZINC OIL ADDITIVE for older engines

Stop listening to media hype.
Zinc is needed for new/rebuilt engines, not forty-four year old engines.
Lead substitute isn't needed either.

HT32BSX115 · Jun 17, 2011

Re: ZINC OIL ADDITIVE for older engines

mkast said:
stop listening to media hype.
Zinc is needed for new/rebuilt engines, not forty-four year old engines.
Lead substitute isn't needed either.

ditto!

Tahorover · Jun 17, 2011

Re: ZINC OIL ADDITIVE for older engines

So Mkast your saying that a marine engine without hardened exhaust seats will live a long healthy life on unleaded gas?

Bondo · Jun 17, 2011

Re: ZINC OIL ADDITIVE for older engines

Tahorover said:
So Mkast your saying that a marine engine without hardened exhaust seats will live a long healthy life on unleaded gas?

Ayuh,... Just like with cars, there's danm few left....

1973 was a Loonnngggg time ago...

Tahorover · Jun 17, 2011

Re: ZINC OIL ADDITIVE for older engines

Bond-o said:
Ayuh,... Just like with cars, there's danm few left....

1973 was a Loonnngggg time ago...

Plenty left there just hooked to a Velvet Drive and not a I/O!

mkast · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

Tahorover said:
Plenty left there just hooked to a Velvet Drive and not a I/O!

And?

redgoat · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

Well thanks for the replies. With all due respect to those who believe that I do not need a fuel additive or additional zinc to my motor oil I must go with the "media hype." I know what my engine was designed to run on and whatever it takes to duplicate its safe and efficient operation as well as protection to vital internal parts I will use. After all, my classic, 44-year-old Sea Ray has not lasted this long by neglect to details and improper maintenance.

mkast · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

If you spent the time to do the RESEARCH, instead of watching a television ad, you would know the "common knowledge" presented here.
Have you read the Mercruiser maintenance manual appropriate to the engine?
Mercruiser does not authorize use of additives in the fuel or oil.

redgoat · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

So what you are saying is that the tetra-ethyl lead in the gas I used in 1967 was really unnecessary and the current 10% alcohol blend is just fine with older Mercruiser engines.

skargo · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

redgoat said:
Well thanks for the replies. With all due respect to those who believe that I do not need a fuel additive or additional zinc to my motor oil I must go with the "media hype." I know what my engine was designed to run on and whatever it takes to duplicate its safe and efficient operation as well as protection to vital internal parts I will use. After all, my classic, 44-year-old Sea Ray has not lasted this long by neglect to details and improper maintenance.

I agree with you. I use an additive in my 1963 Corvette and in my 1967 Pontiac.

Tahorover · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

mkast said:
And?

and what?

wifisher · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

redgoat said:
So what you are saying is that the tetra-ethyl lead in the gas I used in 1967 was really unnecessary and the current 10% alcohol blend is just fine with older Mercruiser engines.

yes

skargo · Jun 18, 2011

Re: ZINC OIL ADDITIVE for older engines

Hey redgoat, I see you tried to PM me but my box was full. I made room, so feel free to resend.

bruceb58 · Jun 29, 2011

Re: ZINC OIL ADDITIVE for older engines

I wouldn't bother with a lead substitute. For the amount of hours that get put on a marine engine, its going to take a LONG time for the seats to fail. Then just get the heads redone! Will be money ahead with all the lead substitute you put in which may or may not actually work that well in the first place.

HT32BSX115 · Jun 29, 2011

Re: ZINC OIL ADDITIVE for older engines

redgoat said:
So what you are saying is that the tetra-ethyl lead in the gas I used in 1967 was really unnecessary and the current 10% alcohol blend is just fine with older Mercruiser engines.

Absolutely right.

The 1966 Mark Twain that dad bought new and I got in 1997, didn't get leaded fuel after it became unavailable continued to run well until I sold it in 2005 and the 150 Mercruiser in it never had the head off.

I can categorically say that lead substitute snake oils are NOT required.

They are more of a benefit to the SELLER than the buyer.

PiratePast40 · Jun 29, 2011

Re: ZINC OIL ADDITIVE for older engines

On the subject of zinc and phosporous, there has absolutely been a change in engine oil composition with the intent of removing the zinc because of it's detrimental effect on catalytic converters (at least that's what I've read). Say what you will about snake oil but I'll side with the classic car guys and my engine builder. When I first spin up the oil pump and when it first cranks, my rebuilt Volvo AQ130 is going to have a zinc phosporous additive in the crankcase. I had to replace the cam because of wear on the lobes on this engine with solid lifters. To me, the cost of the additive is a small price to pay.

And I'm just not going to argue with Don Garlitz!

sasto · Jun 29, 2011

Re: ZINC OIL ADDITIVE for older engines

In my old 1974 I run straight 30wt Rotella oil and 87 octane ethanol fuel with no problems. The PO did the same. I plan on continueing to do so. 1500 hrs later....no worries for me. I agree with some of the guru's here.

Good Luck!

Outsider · Jun 29, 2011

Re: ZINC OIL ADDITIVE for older engines

Should I add this zinc additive to my current 30W oil? and then 24 hours later With all due respect to those who believe that I do not need a fuel additive or additional zinc to my motor oil I must go with the "media hype."

Sooo, you really had already made up your mind, but were just a little insecure with your decision so you came to find someone to agree with you? I believe it was Will Rogers who said there's no reason to ask a question if you know the answer ... :facepalm:

Pete104 · Jun 30, 2011

Re: ZINC OIL ADDITIVE for older engines

Most of the above is true. And more power to you.
Zinc makes oil "stick" to parts. A hot engine shut down, the oil is gonig to disipate from the cam & lifters by the time it's room temp. Zinc holds the oil to the surfaces, thus no dry starts.

ZINC OIL ADDITIVE for older engines

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