After experiencing very good results with MoS2 in a 1995 Miata, including reduced engine noise, increased engine smoothness throughout the rev range, and steady state fuel economy increases of 5-8%, I decided to try it in a couple of other vehicles despite being relatively biased against using additives without a significant reason for doing so.
Due to lots of weather variability where I live, I decided to just measure sound pressure levels using an older Radio Shack 33-2050 sound level meter. The two vehicles are a 1996 BMW with a 2.8 liter inline 6 and 130k miles, and a 2011 Corvette with a 6.2 liter V8 and 20k miles. Tests were done in my garage, with all garage doors opened in every instance. Because I live in a cul-de-sac, I ensured that it was quiet outside when I did the meausrements, and made sure that nothing in the garage such as the HVAC, were on.
I conducted the measurements by having someone else start up the car during cold starts, and held the sound level meter one foot above the centerline of the engine using a ruler. The hood was open fully and held open by the built-in prop struts. On cold starts, I let the engine speed settle for 3-5 seconds until a steady fast idle speed was atttained. For hot measurements, I simply drove into the garage, opened all the garage doors, and did the measurements myself, again using the one foot ruler as a guide. I did several tests before adding the MoS2 on various days and gained a baseline that fluctuated by a maximum of 1-2 db in every instance.
After adding the MoS2, each of the vehicles have been driven between 300-500 miles, and I personally ensured that some of this was during high RPM and high throttle opening driving. This was probably the most fun part of this testing.
Anyhow, here's what I got (hot measurements are without electric cooling fans being activated):
BMW cold:
Baseline: 82-84 db
After MoS2: 77-79 db
BMW hot:
Baseline: 74-76 db
After MoS2: 70-72 db
Corvette cold:
Baseline: 79-81 db
After MoS2: 75-77 db
Crovette hot:
Baseline: 73-75 db
After MoS2: 69-70 db
Both vehicles are driven inconsistently enough so that any fuel economy measurements would be pretty meaningless. The BMW is most noticeably quieter during cold starts. There's a lot of mechanical noise that isn't present any more. The Corvette motor, when hot, was quiet before but is no so quiet that a nrmal speaking voice is clearly able to be heard from someone standing on the other side of the open engine bay.
The BMW is pretty well insulated and I honestly don't notice any difference in sound or smoothness when driving the vehicle. The Corvette makes a lot of exhaust and engine noise and it's also impossible to hear any engine noise changes over that, but it does feel smoother as it revs, though that may be a placebo effect thing.
No oil was changed during this time, and the same gas has been used throughout. Temps have generally been in the 40's and 50's, and nothing has changed within our garage that might absorb sound. The same one foot ruler was used, and A-weighting was used throughout.
Due to lots of weather variability where I live, I decided to just measure sound pressure levels using an older Radio Shack 33-2050 sound level meter. The two vehicles are a 1996 BMW with a 2.8 liter inline 6 and 130k miles, and a 2011 Corvette with a 6.2 liter V8 and 20k miles. Tests were done in my garage, with all garage doors opened in every instance. Because I live in a cul-de-sac, I ensured that it was quiet outside when I did the meausrements, and made sure that nothing in the garage such as the HVAC, were on.
I conducted the measurements by having someone else start up the car during cold starts, and held the sound level meter one foot above the centerline of the engine using a ruler. The hood was open fully and held open by the built-in prop struts. On cold starts, I let the engine speed settle for 3-5 seconds until a steady fast idle speed was atttained. For hot measurements, I simply drove into the garage, opened all the garage doors, and did the measurements myself, again using the one foot ruler as a guide. I did several tests before adding the MoS2 on various days and gained a baseline that fluctuated by a maximum of 1-2 db in every instance.
After adding the MoS2, each of the vehicles have been driven between 300-500 miles, and I personally ensured that some of this was during high RPM and high throttle opening driving. This was probably the most fun part of this testing.
Anyhow, here's what I got (hot measurements are without electric cooling fans being activated):
BMW cold:
Baseline: 82-84 db
After MoS2: 77-79 db
BMW hot:
Baseline: 74-76 db
After MoS2: 70-72 db
Corvette cold:
Baseline: 79-81 db
After MoS2: 75-77 db
Crovette hot:
Baseline: 73-75 db
After MoS2: 69-70 db
Both vehicles are driven inconsistently enough so that any fuel economy measurements would be pretty meaningless. The BMW is most noticeably quieter during cold starts. There's a lot of mechanical noise that isn't present any more. The Corvette motor, when hot, was quiet before but is no so quiet that a nrmal speaking voice is clearly able to be heard from someone standing on the other side of the open engine bay.
The BMW is pretty well insulated and I honestly don't notice any difference in sound or smoothness when driving the vehicle. The Corvette makes a lot of exhaust and engine noise and it's also impossible to hear any engine noise changes over that, but it does feel smoother as it revs, though that may be a placebo effect thing.
No oil was changed during this time, and the same gas has been used throughout. Temps have generally been in the 40's and 50's, and nothing has changed within our garage that might absorb sound. The same one foot ruler was used, and A-weighting was used throughout.