Friday, September 5, 2008

How not to do an oil change

After changing my glow plugs, I was wondering if I'd done any damage to my engine by starting it so hard all the time (it took 3-4 attempts to start it every morning, before I put new glow plugs in).

A knowledgeable friend and fellow van-dweller, who used to be a professional truck mechanic, suggested that the smartest thing I could do is change the oil, even if I hadn't reached my change interval.

So I bought some Rotella, and did the oil change, using an excellent procedure I found on a PowerStroke website.

I made one very stupid mistake that the instructions didn't warn me against: I calculated the amount of oil needed, instead of checking it empircally. The docs on that website said 4.5 gallons of oil. Great. I bought two cases of 3 gallons each, figuring I'd have extra.

I filled up the filter before putting it in. Great. Then I poured in 4 gallons of oil. Then I thought, "Cool, I already have a half-gallon sitting here!" So I poured that in to get 4.5. Are you discovering the math error here?

Anyway, I overfilled the crankcase, big time. I had to get underneath the vehicle, pull the plug, and drain a half-gallon out, to cover the half-gallon I'd already put into the filter. Checked the dipstick, and, whoops, it's still too full! Pull the plug again, pull out another GALLON. Gallon and a half of expensive diesel truck motor oil, wasted and off to the recycling.

The problem is, that on this PowerStroke, the motor oil is used as part of the fuel injection system. So, when I drain the oil, I'm not really draining all of it. There's still a lot stuck in the fuel injection high-pressure pump and lines to the injectors.

The correct procedure, which I should have done first off, is to ONLY put in a little oil at a time, and then check the dipstick. Then pour in some more, check the dipstick again. It looks like this engine may take 4.5 gallons of oil, but when changing it I'll only need maybe 4 gallons, maybe less. That will save me money and time the next oil change around.

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