Briggs 4T custom blended by Amsoil is what we recommend. This was a joint development project to give racers an oil without the severe downside of today’s karting ‘oils’ or the regular issues we see when automotive oils are used.
Most karting oils are simply compressor lubricant and food coloring. They found their way into karting decades ago because they have an initially high film strength, burn clean in the combustion chamber (helping pass the old school you can’t scrape carbon rule to measure piston pop-up), and are cheap allowing for a robust margin. I would even argue that they promote consumption due to their severe limitations (both the change interval just to keep your engine together and in part sales).
PAGs (karting oils) are hydroscopic in nature, pulling in moisture right out of the air. This is the number 1 reason for the failures we see. Typical tested oil samples have 1-3% water contamination. An open bottle in your trailer, a crankcase open to air, the simple cooling of the engine after practice or sun hitting your trailer causes moisture to be absorbed. PAGS have low solubility so additives to help prevent this cannot be added. This is also why racers need to be especially careful when switching from PAG oils. Crankcases need to be flushed to prevent PAG oils from separating (low solubility) and starving bearing surfaces. Think oil and vinegar.
With moisture comes rust and the development of an acid (resulting from the by-product of combustion and water combining). The great initial film strength PAG oils have rapidly unravels when reaching our operating temperature AND turns to vapor out your breather. Gone is your protection.
PAG base oils are NOT used in ANY other form of racing or combustion engines because they simply do damage. While I hear people tell us they have great ‘luck’ running such and such, ‘luck’ is all it is.
Now, onto automotive oils. If it is good enough for your car or race car, it should be just as effective in your kart engine, right? Without naming brands some of the biggest names out there will induce failures in our engines. While grouping oil in this category together is a generalization most are very similar in their base and additives (or lack of). Car engines operate at lower operating temperatures (water verses air cooled). Therefore they are engineered for this environment and above that film strength stability is compromised. The other critical difference is this oil category is they are engineered for a pressure, not a splash lube system. Having the benefit of pressure lube allows manufacturers to save money by not having to add unnecessary additives like ones that help prevent foaming. So when you take a automotive oil and use it in a splash lube system it tends to foam. Air bubbles across a bearing surface is an area without proper protection. Even some of the most expensive automobile oils induce repeatable failures because of these shortfalls.
Briggs 4T is our effort working with Amsoil, the leading synthetic manufacturer in the industry, to provide an oil that matches the performance (power) of it’s peers but goes beyond with an additives package that maintains film strength over time and/or in the event of fuel contamination, and rust and wear inhibitors.
Simply put, Briggs 4T oil matches the effort and engineering we put into each engine. It’s an oil we confidently know will give racers the best experience and life from their engine.