Oil type

[pablos]

I just purchased a 1983 Kawasaki LTD 750. The previous owner used regular 20-50w automotive oil. Should I keep using this or change to a synthetic?

Whats the best choice of oil?

thanks

[07Ninja250]

One disadvantage to changing an old bike, car, etc. over to synthetic is that if you have a compromised seal somewhere that's being held shut by the smallest amount of sludge, synthetic oil tends to clean away the 'sealant' and accelerate the leak. I experienced this on my previously non-leaking 1978 Chevy Monza, which had a sudden rear main seal leak after switching to syn.

If through the magic of a crystal ball you happen to know that all your seals are in excellent shape, synthetic would be fine. Just don't be surprised if the engine starts consuming oil. That's the other disadvantage that seems to be hit and miss from one engine to the next. Syn can find its way past worn rings where conventional didn't. My 1986 Civic Si was a prime example of this. I switched it back to Castrol GTX so I wouldn't have to top it off between oil changes.

Sometimes the consumption slows and stops after the switch, sometimes it continues on to the end of time. My 2004 Troybilt mower with a 6.5 Briggs consumed no oil on straight 30 conventional, but consumed an alarming amount of 5W-30 and 10W-30 synthetic. 10W-40 syn slowed it, and 20W-50 syn stopped it. It depends on how well your rings have stood the test of time.

Personally, I prefer syn for a hard working motorcycle engine...especially air cooled. It resists coking, shearing and thermal breakdown better than any conventional. Unfortunately, if it causes a compromised seal to start leaking, there's no going back. You live with the leak, or replace the seal. Consumption can most often be reversed by going back to conventional or thickening up the syn. If you're already using 20W-50, of course thickening wouldn't be advisable.

Good luck with your decision.

[elr658]

Shell Rotella Diesel 15w-40 was good enough for a 9 second quarter. Good for wet clutches and runs in everything I own.

[northernman]

Originally Posted by elr658

Shell Rotella Diesel 15w-40 was good enough for a 9 second quarter. Good for wet clutches and runs in everything I own.

+1 great stuff.

[herk]

The Shell Rotella-T 15W-40 usually costs less than the others too. AAA+++

Alternatively, you could use Chevron Delo - I've never used it, but it's also a heavy duty oil that's marketed for diesel engine use.

[Lawn Masters]

I'll give the Shell Rotella T another vote here. I run it in my ZX1000, and will be in my CB750 when I've got it running.

its great stuff for motors that see a lot of friction and stress like ours do.

[Hot Cruiser]

Originally Posted by 07Ninja250

Sometimes the consumption slows and stops after the switch, sometimes it continues on to the end of time. My 2004 Troybilt mower with a 6.5 Briggs consumed no oil on straight 30 conventional, but consumed an alarming amount of 5W-30 and 10W-30 synthetic. 10W-40 syn slowed it, and 20W-50 syn stopped it. It depends on how well your rings have stood the test of time.

Yep, interesting situation with B & S air cooled engines. I've always run straight 30 conventional Castrol car oil in mine, even in my 20 HP 2-cyl. lawn tractor and they never use a measurable drop. A neighbor asked me to check her lawnmower oil level, with the instructions pasted by the filler saying to use 10-30. The dipstick showed oil right at the very bottom. I put in 10-30 since that's what she had and after she ran the mower for half an hour the oil level again was at the very bottom of the dipstick. Changed the oil and put in straight conventional 30 - now doesn't use any oil. But my last air-cooled motorcycles have used multigrade - 10-40 or 20-50 and don't use any oil between changes, and I use Castrol GTX. Maybe there's something about B & S engines - ring clearances or something similar - which causes them to burn lighter multi-viscosity oils, whether regular or synthetic.