Piston Slap: There's Gold in Them There Oil Changes

Sajeev Mehta
by Sajeev Mehta
piston slap there s gold in them there oil changes

TTAC commentator bumpy ii writes:

I have an S2000 with just over 50,000 miles on the clock. The first thing I did when I bought it three years ago was to change the oil to Mobil 1 10w30 and install the OEM filter. I’ve put about 4,000 highway miles and a few autocrosses on the oil since then, with two or three minor top-offs. I’m planning on changing the brake fluid and coolant this summer (did the transmission and differential last summer). Should I change the oil too, even though it’s still that happy golden color? How about the filter?

Sajeev answers:

The oil is still golden? That comes as no a surprise, and that means you’re fine for several thousand more miles.

On one hand I’ve heard of tow vehicles going to/from the Bonneville Salt Flats needing 10,000+ miles between M1oil changes, because highway cruising is easier than bumper-to-bumper traffic, especially in hotter climates. On the other hand, I’ve had two overheating issues while (ahem) legally racing, which sadly wiped out once-good M1 in a matter of minutes.

But those are extremes: for your car, I would be hard pressed to change M1 oil before 5000 miles. Having 4000 miles on M1 is no big deal for almost any driving condition, but three years between changes is.

Change the oil.

[Send your technical queries to mehta@ttac.com]

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4 of 23 comments
  • Mikey Mikey on Jun 09, 2009

    @sajeev your not the first guy to tell me that,so I will do the oil analysis and find out for sure. If I'm wrong,next time I'm in the US I'll send you a 6 pack of Labbats 50.

  • Albert Albert on Jun 09, 2009

    In general engine oil is fully used after this period. Remember that this kind of usage (5.000 miles in three years) counts as severe usage. Why should you bother? If you can aford this car, you can afford an oilchange. What you can't afford is extreme engine wear (and that comes sooner than most people believe). AFAIK the recomended viscosity is 5W-40. The differentials need HP GL-5 80W-90

  • Sajeev Mehta Sajeev Mehta on Jun 09, 2009

    mikey : email me with your insights from the oil analysis, it'll make Piston Slap for certain. And I have friends and relatives in Toronto who wouldn't mind mailing you a 6-pack of joy for your trouble. :) -------- Joe O : To Sajeez, the fact that you indicated oil color gives any information is disturbing. While low-mileage golden oil may have hidden problems, do you really think that dark-as-night oil is telling you absolutely nothing? Color gives information.

  • Joe O Joe O on Jun 10, 2009

    What information is that? Colored oil viewed on a dipstick imparts no real information. Now, granted, you pull the dipstick and a wad of sludge falls off, or you feel grit between your fingers, that'll tell you something. But the color does not. Midnight black oil represents suspended combustion blow-by. Doesn't represent the protection afforded by the oil, it's viscosity, it's remaining additive packages, or many other actually important values. That's why some cars turn oil black in 1000 miles and drive on it for an additional 4000 miles without problems, and other cars look like amber after 15000 miles on the same batch. Joe