would like to thank Jonesie from www.thedieselgarage.com for taking the time and doing this test for us.
OK boys and girls.........the results are in-
Here is the setup:
Does 2 cycle oil actually quiet the engine, or is it all in our warped minds??
For the test:
I parked my truck in it's usual spot on the driveway Placed a tape measure on the ground perpendicular to the left front wheel Placed a digital sound meter on an 8" high photo tripod with the sound pickup at 36" from the wheel. Recorded sound measurements on fast response, "c" weighting and adjusted scale for decibel range.
Sound measurements were taken with truck at operating temperature, no accessories on (a/c, htr., lights, etc.) Measurements recorded for truck at idle and 2000 rpm in park, auto trans. Setup was duplicated for straight ULSD and 128:1 2 cycle oil mix, both tests conducted at approximately 6:30 pm PDT., several days apart.
Test #1- 128:1 2 cycle oil (I already had the mix on board, so I ran this test first):
Reading at idle- 79 db
Reading at 2000 rpm- 89 db
Test #2- Fuel tank run as low as I dared, then filled with straight ULSD, driven for 125 mi., then tested:
Reading at idle- 84 db
Reading at 2000 rpm- 92 db
The addition of 2 cycle oil at a ratio of 128:1 (or 1 oz/gallon) attenuates or reduces the sound generated by the diesel engine at idle 5 db, and 3 db at 2000 rpm.
Subjectively, the tester felt that the truck ran more smoothly overall and displayed less perceived vibration in-cab with the addition of 2 cycle oil, and also the 5 db sound attenuated recorded was easily noticed both in-cab and standing outside.