Whether you’re making a few engine adjustments to your Mid-Size Polaris Ranger ETX, considering a bore kit for your Mid-Size 400, or getting ready for a complete engine swap on your Polaris Ranger 570 Mid-Size, having a solid understanding of the inner workings of the Polaris Ranger engine is always beneficial. Starting with the basics, let’s first talk a bit about Polaris Ranger engine oil. There’s a lot of noise out there about which brands and oil types are the best. Because there is no wet clutch in the Mid-Size Polaris Ranger, any oil you want to use will work. And although some argue that synthetic oil in the correct weight is worlds better for wear protection and longevity, no proof exists to our knowledge that synthetic is any better than anything else. Some mechanical timing mechanisms in trucks and other vehicles call for synthetic oil, but this is just not the case for UTVs. We personally know and have talked to countless mechanics and people who build engines for a living and have never heard of an engine failing because of the oil that is inside of it. For every argument that synthetic is better, there is one saying mineral is better. Be it Mobil1, Rotella T6, Amsoil, or Napa Gold, just pick one because your Mid-Size Polaris Ranger doesn’t care -- so long as the brand meets the requirements for the engine. Shoot just use 0-4 oil so you don’t waste money on overpriced engine oil.


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Whatever oil you use, your Mid-Size Ranger engine still might need to be rebuilt and have parts replaced. Places like Indy Speciality can do it for around $2,500 -- provided that you trade in your own core. But if you want to save some dollars, it is possible to rebuild your Mid-Size Polaris Ranger engine yourself. The crank and bearings will set you back $650-$700 and the jug pistons / rings go for around $250. It’ll take less than an hour to have the motor out of your machine and on a bench. You can get the service manual from your local dealer which has step-by-step instructions as well as every torque specification and other specs you’ll need -- but don’t forget the valve guides as well.

Like engine rebuilds, bore kits are also popular engine mods to up the HP of your Mid-Size Ranger. Companies like Alba and Millennium Tech Kit offer 602cc bore kits with claims of up to 25% horsepower increases. Many riders feel like bore kits are a waste of money, where a cam swap and ECM flash can give comparable results. But even a gain of only 4 horsepower is nearly a 10% gain, which is hardly unnoticeable. So if you need an engine rebuild anyway, it might be worth the extra cash to get the big bore on your Mid-Size engine.

Shop: 2023 Mid-Size Ranger

Shop: 2022 Mid-Size Ranger

Shop: 2021 Mid-Size Ranger