After reading this thread -
http://ecomodder.com/forum/showthrea...wners-128.html
I decided to try a different type of oil in my Citicar transaxle. Originally, this vehicle was supposed to use 90w gear lube.
When I bought the Citicar two years ago, the transaxle/differential was quite noisy and I only drove it a few miles before I drained the oil. The transaxle (single speed, direct drive, no ring/pinion gear, just straight cut gears) had a couple ounces of sludge inside that looked like really thick Testor's silver model paint. I refilled the axle with conventional 90w gear oil, but the sound didn't change much.
For those of you have not been in an electric car, the gearbox is one of the main producers of sound. With no engine, one hears different aspects of a vehicle! The gear sound in my Citicar was bothersome enough that I eventually took the transaxle apart to see if there was a problem, but didn't find any significant issues.
I refilled the axle with 75w/90 synthetic (Valvoline). This made the gear sound somewhat quieter, and less tinny. BTW the oil no longer has the metal flake look... The original discoloration may have been break-in wear.
I drove it using the 75w/90 for the past year. This week, I changed the oil to Pennzoil Synchromesh manual transmission oil. It is supposed to be about 80w, but flows much faster out of the bottle than did the 75w/90.
The gear sounds from the transaxle are somewhat different, and seem to be a bit quieter. Near the end of a 20 mile drive today, I was able to get to almost 37 MPH, about 1 MPH faster than normal even though the batteries were about 70% discharged at that point. The Citicar now appears to coast farther than it used to. But most of that is subjective, and may be wishful thinking. I keep watt hour/mile data on this car regularly, and should have some objective results in a few weeks.