Oil for gas powered splash lubed engines

[rkcarguy]

I figured I'd get up on my soapbox again regarding oil, as I've done a lot of research and a lot of learning the hard way on this one.

Those of you with gas powered splash lubed engines will want to pay attention.
No that long ago, the EPA mandated the removal and minimization of additives like zinc, sulfur, and moly in "on-road" motor oils. This is far reaching, affecting every oil type and brand from the 99 cent a quart stuff to Mobil 1 full synthetic, and in my opinion is one of the least known and most BS move in automotive history if you ask me.

Here's the deal. In newer car motors with oil pumps and roller valve train with minimal "rubbing" parts, it works fine. In a splash lubed flat tappet engine that many use in their locomotives, tillers, lawn mower, go kart, or whatever, these additives are vital to the continued lubrication of the crank and rod, camshaft lobes, and cam bearings. Note that the rod/crank, and cam/case bearings are steel on aluminum, there is no bearings or bushings here so if the oil is working poorly the aluminum gals quickly and seizes the engine. I started seeing a lot of metal in my oil on two engines, and lost two engines to seized connecting rods which ventilated the block in spectacular fashion, running Mobil 1 synthetic and Castrol full synthetic. Both motors had broken in fine on regular cheap oil. Come to find out, my cheap oil was old stock chevron oil with about 1300 PPM(parts per million) zinc. The Mobil 1 only had about 500, the Castrol had none.
The BMW guys were having so many issues with cam lobe wear and valve train problems that one online forum started a group buy of bulk volumes of euro-spec Mobil-1 which still had the additives in it, and were shipping it stateside.

The solution I found, is that off-road racing oils, motorcycle oils, and marine oils still contain the additives we need. Of the SAE ratings, "SG" was the last rating that included a minimum of 1300 ppm zinc. We are at "SN" now, which is bathwater as far as I'm concerned.
I have personally had good luck with Maxima motorcycle oil, it has nearly as much zinc in it as Amsoil plus great anti-foaming properties, I don't even need to run the synthetic, the synthetic blend works fine on my racing kart and for equipment I just use the full petroleum version.
When looking for your oil, look for "meets and/or exceeds SAE SG standards", this will assure a high zinc motor oil. Kawasaki and several other motorcycle manufacturers even require this to honor their warranties if you read the fine print. Many generator and equipment companies that include the first fill of oil with their equipment will also include a "SG" rated oil if you look at the bottle.

(steps off soapbox)

[Steggy]

It should be noted the operator's manual for Briggs & Stratton V-twins recommends the use of multigrade synthetic motor oils. If using petroleum-based oils, straight SAE 30 is recommended if operating the engine above 40° F (4° C). Any motor oil that is suitable for use in an automobile engine is suitable for use in any air-cooled small engine produced in the last 15-20 years.

All air-cooled engines stress the oil more than liquid-cooled engines, so the type of oil used is critical to obtaining long engine life, as is regular oil changes. Motor oil additives deteriorate over time, as well as due to use, so change the oil (and filter, if present) regularly. Changing the oil a lot cheaper than replacing the engine after it ejects a rod through the side of the crankcase.

[rkcarguy]

http://www.sportrider.com/oils-well-ends-well-part-1

This is a good read. One can see in part 2 that these oils have lots of wear preventing additives. Base stock of the oil is also very important though, as shown here:

http://www.camaros.net/forums/134-tips- ... sults.html

Some very expensive oils were total fails or mediocre protection, while some cheap stuff has the formula right.

I've made changes since I found this out, and my stuff ALL runs better and lasts longer.
BDD, I only run my kart oils for one hour of track time and then change them. Both engines that failed were FULL of fresh oil, it just didn't look like it worked at all.

[rkcarguy]

I wanted to add as well, that to put an end to a similar post/argument on the karting forum several years ago, I wrote Mobil-1 and the Castrol guys, and BOTH responded saying NOT to use their on-road car oil in splash lubed engines.
It is the nice thing about the V-twins, is once you get up past the single cylinders most companies put an oil pump and filter system in the motor.