Toro 8-32 with 8HP Briggs, using oil

[spinfire]

I bought a house and with it a Toro 8-32, I think from 1990. The engine is a 8HP Briggs & Stratton.

I mow probably about an acre - maybe an hour and a bit total time. During this period the engine seems to burn oil - about 4 ounces based on the fact that the lower end of the dipstick range says "Add 8 ounces". I have been checking the oil when the engine is cold, and adding a bit before each time I use it. I'm using Castrol GTX 5w-30, although I also added a bit of Rotella T Synthetic 5w-40 when I didn't have any of the Castrol.

There is no visible blue smoke when mowing, but if I let the mower idle for a bit it'll puff a bit as it idles - and a bigger puff of blue smoke when I rev it back up to mow. Is this a normal amount of oil consumption for this engine?

Any comments on choice of oils? I'm also running a bit of seafoam in the gas right now to clean out the carb.

 

[JTK]

Looks like a good old mower! Given the vintage and what you describe, I'd run the least expensive house brand 15w40 I could find. No sense in blowing $ synthetics out the exhaust.

Joel

 

[spinfire]

Yeah - it is a workhorse. It was "as is" with the blade bent from hitting a rock. I put a new blade on and it works great.

I'm running the Castrol GTX because I have a ton of it. I put the Rotella in before we'd moved to the property and I happened to have Rotella in my trunk. The manual recommends 5w-30 during winter months and straight 30 weight in the summer. But you recommend the much thicker 15w-40... is that just because of the age? Any concerns running the thicker oil?

 

[JTK]

The thicker viscosity range will tend to blow past the piston less than a 30wt, thus less oil consumption. I wouldn't run it for cold weather starting, but with a mower that's usually a non-issue.

Joel