I have been running low gears in a zuk for about five years, I have learned one thing about samurais they do not like royal purple or any other synthetic oil, also I have tryied lucas and stay lube and did not like them either, took them back out quick, went to mystic oil and never looked back, on the engine i went to a cheaper chevron oil because I change it alot about every one thousand miles and add a half a bottle of prolong every time or so and went to a napa nascar oil filter made by wix, and a I went to a ford 3.0 engine filter (larger) for like an 1989 ford taurus, have worked out great for years, the synthetic oil has no shock loading for off roading so your gears clash all the time (it's like gasoline in your gear boxes) it's so thin, and at 4 bucks a quart for mystic thats not bad, I use 1 qt in my x-fer case 1.5 abouts in my trans and about the same in my diffs, I buy 8 quarts and just dump them in my paint pot and a bottle of prolong for trans when I change out my fluids so i'm not real exact but prob. close but I can change them a couple of times with that.