ARx in Corvette LT-4

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This note Added at 2215 PDT 30 Aug 04:
Just got T. Dysons evaluation of the latest UOA. He credits ARx with some of the improving trends in the engine oil. So it looks like ARx did do something for my engine, although it still didn't remove any noticeable crud as shown by the clean filter elements.
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I used ARx in my 1996 Corvette LT-4. The engine, transmission (manual) power steering and differential all got the recommended amount of treatment, although I did run over the recommended miles on the clean cycle for everything except the PS.

Car was bought used in November 2003 with 39,500 miles and an unknown history except that it was "dealer maintained". It is in excellent cosmetic condition and excellent mechanical condition except the excess lead and tin in the UOA. It runs like a new car. It had a fresh oil change with M1 5W-30 when I got it.

I put the ARx in everything with 41,500 odo miles. That was 2,000 miles on the M1 5W-30, unknown mileage on the other fluids.

Engine:

I new this was going to be a tough test for ARX because the engine ran strong and smooth with no noticeable faults and gave good gas mileage. Looking inside the oil filler hole, the head surface, visible valve spring and rocker arm looked like new parts that someone has poured fresh oil on. Not even any signs of varnishing discoloration. There was no room for improvement in visual cleanliness.

ARx claims to do good things for low mileage engines and sez look in the filters afterwards to see what it did, so although sceptical, I decided to give it a try.

Took off the Fram Duraguard filter the dealer had installed, installed a Fleetguard LF3554 synthetic media filter, installed the ARx and topped the oil level back to full.

Ran ARX clean cycle 4,000 miles, didn't notice any difference during clean cycle.

Changed oil to Mobil Delvac Super 1300 15w-40 and installed a new Fleetguard LF3554 filter. The M1 with 6420 miles wasn't particularly dirty and was in decent condition. UOA is at

After a couple of hundred miles I started getting some lifter like noise on startup. It was intermittent and happened with the engine warm or cool. By end of clean cycle, the lifter noise seemed to have gone away completely.

After 2,950 miles clean cycle, drained the S1300 15W-40. It still looked fairly clean and had a TBN of 8. Also reported in the above UOA. Replaced with M1 10W-30 and 5 oz of LC. Also installed new LF3554 filter.

I cut open the Fram filter I took a off before the test and the two Fleetguards I used during the test. Opened up the filter media and spread it out to take a good look at it in the sunlight. None of the three elements had any particles or sludge that showed to the naked eye. Also looked over a few pleats with a hand held magnifying glass. There were a very few small particles, some metallic looking on all three elements. No definite difference in quantity between elements. Overall, some of the cleanest elements I have ever seen. No sign of ARx doing anything was found by looking at the filter elements.

Gas mileage was close to 27 mpg by trip computer on a 150 mile trip I take about once a month. It's relatively flat, mostly freeway mostly 70 to 75 mph cruising with some traffic. If traffic gets worse, mileage drops so it isn't a useful mileage run.

There was no significant change in gas mileage during or after the ARx runs. It still approached 27 mpg after about 150 miles of driving.

Transmission:
This was another tough test for ARx.

The transmission is a ZF6 speed. It shifted smoothly and was as quiet at Corvette ZF 6 speeds normally are. It also had a recently installed Hurst kit to shorten the shift throw. A very sweet transmission, and very expensive one to rebuild if it ever needs it.

The already smooth shifting transmission seemed to get a bit smoother about 1000 to 1500 miles into the clean cycle. I suspect this had something to do with the ARx. A bit more verbiage and a transmission UOA at

Differential:
Another tough test for ARx because no problems existed before adding ARx. No improvements were noted after ARx.

Power steering:
The PS fluid that cam with the car looked and smelled badly burned, but didn't have visible crud in it and hadn't left solid deposits in the reservoir.

Before I started the ARx test, I did 4 changes of the reservoir oil using Valvoline synthetic PS fluid. Drove the car 20 to 100 miles between changes. Total system capacity is 1.5 pints (per the shop manual), the reservoir holds 1 pint. By the numbers that left a bit over 1% of the original fluid in the system after 4 changes. It was improved a lot but still smelled a bit toasty. I let the ARx work it's magic for about 1500 miles and then changed the fluid once more, this time to Redline PS. The smell was virtually gone. Since the 3rd to 4th fluid change made little difference in smell, I think the ARx helped a lot here. Now, 5,000+ miles later, the fluid still looks and smells good. A win for ARx.

Summary:
It did about as I had expected
Engine: No improvement
Differential: No improvement
Transmission: Probable improvement in shift smoothness
Power Steering: Pretty sure it did good cleaning job.

I have started and ARx cycle in an Acura 3.2l V-6 with about 86k miles and GMC 4.3l V6 with about 100k miles. In process reports to come in a few weeks.

The Acura test will also be tough on ARx. The engine looks spotless inside the valve cover, nearly as good as the Corvette did (Gotta love what M1 on 6k mile changes does for a good engine). The GMC looks good for a 100k mile, some deposits ion the valve gear but isn't real cruddy. I have a borescope on order and should be able to get some through-the-oil-filler pictures before, during and after photos on those two engines.

August 31, 2004, 01:36 AM: Message edited by: XS650
 
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quote:

Originally posted by sprintman:
I wish you had done before and after compression tests

It would have been interesting, but I don't expect it would have shown much. With no difference in gas mileage and no obvious difference in performance, there can't be much difference in actual running compression ratio. Perhaps a bit more in the cranking compression ratio.

In the past, I have also found many well cared for engines with this mileage and more to have like new compression during a cranking test.
 
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