Best oil? High zinc?

[bertsmobile1]

I'm down in deep South so my Dealer recommends 20-50 semi K-Tech..

For the 10,000th time
It is a f###ing mower not the space shuttle or a NASCAR top fueller or a Paris-Dakar dirt bike
The zinc content will make absolutely no difference

 

[Hammermechanicman]

 

[7394]

 

[Tiger Small Engine]

Four pages and still going,
We are talking about mowing,
The tried and tested oil debate,
Ain’t opinions and free speech great!

 

[7394]

 

[Hammermechanicman]

My oil is better than your oil but not as good as scrub's.

 

[7394]

Yea sure, bet you say that on ALL the oil threads... LOL

 

[GrumpyCat]

Well... Briggs DOES say that, to keep your warranty valid, you must use their oil, which has high zinc content.

15 U.S. Code § 2302 - Rules governing contents of warranties

www.law.cornell.edu

(c)Prohibition on conditions for written or implied warranty; waiver by Commission
No warrantor of a consumer product may condition his written or implied warranty of such product on the consumer’s using, in connection with such product, any article or service (other than article or service provided without charge under the terms of the warranty) which is identified by brand, trade, or corporate name; except that the prohibition of this subsection may be waived by the Commission if— ...

Then tell B&S they owe you free oil for the duration of the warranty. Per above US code.

 

[GrumpyCat]

When people say high zinc, that's a shortcut for saying high ZDDP (Zinc dialkyldithiophosphate).

As I understand it:
- ZDDP raises the thermal conductivity of the oil allowing it to carry more heat. This is more important for aircooled engines because the oil is the coolant that carries the heat to help it get out to the cooling fins.

"Thermal conductivity" is not the same thing as "carrying more heat". In general the more one carries in suspension in a fluid the lower the freezing point. That doesn't help motor oil.

I seriously doubt the specific heat (the property of "carrying" heat) is significantly changed from 700 to 1200 PPM ZDDP.

- ZDDP creates a film on metal parts that helps them slide against each other with reduced wear.

Such a film is consumable. That means zinc gets crushed when metal parts push through the oil layer. This is why I say a design is defective if it requires zinc to protect cam lobes and lifters.

- ZDDP also creates a film on the platinum in catalytic converters which causes them to prematurely fail.

The phosphorus of ZDDP is the problem, not the zinc.

- Lawnmower engines don't have catalytic converters, so high zddp causes no problems.

Lawn mowers have soft valve springs and low lift cams.

Saw a YouTube video this week were Taryl Dactal thought an engine had a bad compression release. Removed the cam assembly. I didn't know some small engine camshafts were plastic. Ultimately the problem was not the compression release but stuck rings.

Around 2010 automotive oils were mandated to have zinc reduced to 800ppm. Prior to that 1500ppm was normal.

1200 was the limit beyond which acidity becomes a problem.
And only some oils contained more than 800 ppm.

Air cooled engine oil is essentially what normal automotive oil used to be. If oil has an API rating beyond SL then the zinc has been reduced.

There was no requirement for ZDDP so there is no assurance ZDDP has been reduced because there is no assurance it was over the limit.

Putting automotive oil in your aircooled engine is much better than low oil or no oil, and I don't think anyone is saying your aircooled engine will blow up if you use automotive oil. But aircooled engine oil should allow it to run cooler with less wear and have a longer life.

My Kawasaki FR-541V-600V manual states, "API Service Classification : SJ or higher class." Neither "zinc" nor "zddp" appear anywhere in the PDF. No "API SJ to SL" or anything like it.

 

[Hardluck]

Wow. This is getting to he a very technical discussion.
Who knew small engines required such high tech oils.