Thanks Harrier, for clearing that up!

I came across a number of links a few days ago that might be helpful to anyone with questions about his/her powertrain. I've often recommended oil sampling as a regular annual checkup for engine, transmission, or gearcase oils as an "X-Ray" of what's going on deep within the recesses of your vehicle. I learned this was a normal procedure on turbojet engines some years ago, and later adapted the procedure to the engines on my boat, since a failure in either could mean more than a "long walk home". With the price of a Lexus engine so high, it might justify applying some of these procedures to your car's maintenance schedule, too.

Starting with a minimalist kit that includes a small hand vacuum pump and a stack of 1/2" filter pads, a rudimentary microscope, and a couple bottles of test strips, the basic testing tools are a little pricey. Better yet, just buy a few sample containers and send a sample to a pro lab for a quick analysis (starting at about $25). These tests, applied regularly can head off big, expensive problems and ensure your mechanicals are happily doing their job. Ask your mechanic, or contact a local shop that works on industrial powerplants or over-the-road trucks for local pricing.

What does it give you? Sending in a regular sample for analysis, annually for most street applications, more often for high-mileage, high-performance or racing conditions can generate several reports:

1. Wear analysis - monitors machine wear by detecting, identifying and assessing the amount and type of metal wear elements found in used oil.

2. Chemical and physical tests - detects the physical presence of unwanted fluids (water, fuel, antifreeze) in the oil.

3. Oil condition analysis - identifies loss of lubricating properties by quantifying combustion by products (soot, sulphur, oxidation and nitration products).

(above courtesy of Caterpillar)

The first sample I did on a big 351 MerCruiser using a hand vacuum pump, pulling about 20 ml of oil through a filter pad, under a microscope showed a few tiny crystals of quartz - sand - were present in the lubricant - in a brand-new engine. That scared me until I realized that without an air filter (marine engines use flame arrestors only) I should expect airborne contaminants in the oil. With no safe way to properly filter intake air under USCG regs, I moved my bilge vents and upped my oil change schedule. That was a pretty graphic lesson for me.

Oil sampling, including some pretty elaborate procedures, is a common part of PM on most industrial powerplants, but can be a real asset to maintaining your own vehicle - or a good evaluation technique for checking out a used car....like a compression check.

 

Oil analysis is used by big trucks, tractor-trailer, farming equipment fleet owners where changing oil could mean 20-100 qts a shot. And it's only used to determine the optimum change interval, not on a regular basis. Many European-built trucks and buses have oil life monitor nowadays.

For cars that use 4-5 qts at a time (about 5 bucks,) don't bother. Just follow the manufacturer's interval.

 

I agree 100%. I know a man who changed the oil on his 1978 Cadillac Sedan Deville that he purchased with 1800 miles on it. He changes oil every 1500 miles and now has about 230,00 miles on it, and I have heard it run and it is as quiet and powerful as can be. I asked him why he changed oil so often, he told me he has never had a mechanical repair on the original engine and as he put it "do I look like I work for GM?"
He also has a 79 Cutlass 3.8 V6 that has over two hundred thousdand on it and a 58 Chevrolet pickup that he purchased in 58 with 71,000 on it.
The Cutlass has the origninal engine in it and the 58 had a new engine put in it in 59' (factory recall). Both have had the oil changed every 1500 miles. They both sound like new. I change our RX and Camry every 2000 or less. Oil is as an earlier thread mentioned "cheap, smart insurance."

 

I think engine sludge does apply to 99' RX. I just had a 90k miles service done at the dealer. It included tranmission fluid change. And I change the oil every 6k miles. I do gas it pretty hard. Lucky, my RX still doing great.


99' RX 100k miles