[Kracka]

As many of you know I'm a big advocate of conventional oils which is what I ran in my 5 DSM's, my S2000, and my wife's WRX. The only reason I run Mobil 1 (synthetic) on my Evos is because it's factory-fill and I'm also a fan of picking something and sticking with it for the life of the engine. I ran M1 10W-30 (factory-fill) for the life of my IX but just switched my factory-fill M1 5W-30 to 10W-30 in the X.

In the DSM's I was always a fan of the Rotella-T (either 10W-30 or 15W-40). The WRX gets 5W-30 Chevron Supreme and my S2k got 10W-30 Chevron Supreme. Chevron Supreme is one of the top conventional oils and if you catch it on sale or with a mail-in-rebate it can be very cheap. Havoline is probably the best major conventional oil there is, but you pay for it with prices nearing that of synthetics.

Oil change intervals are something that the majority of people do way too often. I ran my S2k and run the WRX on 5k change intervals with conventional. People need to remember that color is of no indication to the oil's quality or remaining life. To learn that info you will need to send a sample in for analysis (Blackstone Labs for example) and look at the remaining TBN which basically shows how much active additive package is remaining. Extended drain intervals are the one major advantage that synthetics have over conventionals. Most of us could easily run 10k+ miles with any of the available synthetics and never see an issue. On the X for example, Mitsu recommends oil changes every 5k miles, but filter changes only every 10k miles.

The better oil filter you run the longer your oil will last. OEM Mitsu's filters are a great filter to go with because they work and they are <$5 with the discount at dealerships. WIX is another popular filter but I've had issues with them so I won't personally recommend them. The Bosch/Mobil 1/K&N filters are all very good (and identical internally). The best bang for the buck filter is the Purolator PureOne gold oil filter available for ~$4; it's quality rivals that of the previous three mentioned but with superior filtration ability. I run these "gold" filters in the WRX and am tempted to switch the Evo over, but Mitsu filters have served so well for so long it's tough to argue with something like that.

The only oil that I really recommend against is Royal Purple and that is due to it's very weak additive package. Fresh from the bottle it's a great oil, but the additive package is junk and gone within 2k street miles.