Originally Posted by RIWWP (Post 3664007)

Premix (Copied from the Newbie's Modding thread, if there are variances between them please send me a PM so I can correct)
Premix thread: https://www.rx8club.com/tech-garage-...-thread-99636/
Premix is mixing 2-stroke oil with the gas in the gas tank to assist with lubrication of the apex seals. Why 2-stroke? Because 2-stroke (in general) is designed to be burned. Unlike 4-stroke that you use in during oil changes. Why premix? This gets a bit more vague when answering. The short answer is as noted, to assist with apex seal lubrication. But do we need it? That's a tougher question to answer with facts. Some people swear by it, others do just fine without it. Series 1 has 2 injectors pointing at the side seals, Series 2 adds a center injector to help with lubricating the center of the apex seal. Mazda added this, so they must have found excessive wear in the center of the apex seal, so it's circumstantial evidence for the need to premix. It's hard to say if this will save your engine from apex seal wear failure though. About the only confirmed difference premixing really makes is that the carbon buildup inside the engine appears to be "softer". In theory, makes it easier to clean, and if it comes off it won't come off in dangerous flakes that could cause carbon lock.

Which premix to use? Lots of debate here too. There are lots of options, and not all of them are even oil. The list below is ordered from most ideal at the top, least ideal/not recommended at the bottom.

Idemitsu Premix is generally considered to be the best out there. The only draw back to it is accessibility in that you have to order it, and there are minimum order quantities. Often a member here will order a larger case and split it with locals, making this a bit easier, but it's also usually a 1-time thing.

Amsoil Saber Pro is highly regarded, and a bit easier to get than Idemitsu.

JASO FC and ISO oils basically other oil brands of the same type and grade as the two items above. May be easier to obtain than those.

TWC-3 Oils are usually easy to find, however it's not likely that you are doing much good with them. Not much harm, but small engines that require this type of oil can fail due to lack of lubrication from it, so it might not be sufficient for us. Post from Emery on this:


Marvel Mystery Oil (MMO) is common, and easy to obtain. Some people swear by it, others denouce it totally. The people that love it can't prove that it does anything good, and the people that say that it is worthless can only point at it's cleaning agents as being a problem, which doesn't even sound like it's that big of a problem. All in all though, it probably doesn't have much lubrication compared to some of the other options above, so it could be considered to probably be on the same level as TWC-3. I.e., not doing much.

Lucas Upper Cylinder Lubricant (Lucas UCL) is a non-oil you can find out there, but we can't recommend it. We can't prove that it causes any fuel filter problems, but for some unknown reason it shows up in a significant percentage of fuel filter problem threads (>2 in 3 threads at a guess). Doesn't even make sense why it would cause problems since it's still just a liquid that can go through the filter, but often fuel filter problem threads include the owner using it for a while before hand, and then stops using it and the problem clears up.

How much premix? The standard amount is about 1oz for every 2 gallons of gas. Some people go 1oz for every 3 or 4 gallons, and some go for 1oz to 1 gallon. 1oz for 1 gallon is getting on the high end though, so don't just use that to use it. Dig into why you want that much. One of the common reasons for going to 1oz to 1 gallon is for a track day. Lots of heat means a bit better lubrication could be a good thing in the end. Note that these values are for how much fuel you are putting into the gas tank. So if you are filling up at halfway and adding 7 gallons, then about 3.5oz is ideal. If you never fill till the light comes on, then around 6.5oz is more accurate. Some premix containers come with a measuring method built right into the top, otherwise it might be useful to find some small plastic containers of the ideal size to keep several on hand. I lost them in a prior move and haven't replaced them, but for a while I was using four 6oz bottles that were originally intended for hair products. Clean them out thoroughly, let them dry, fill ahead of time, and keep tucked in the car to easily add when I fill up. If you opt for this and don't use glass bottles, I'd recommend replacing the bottles periodically, maybe every 6 months. Most plastics aren't of a grade that is designed to hold petroleum products, and it will start to break down from the inside after a while.