Oil... Synthetic or not?
 

Hi Cub community, I have a '75 Cub 1000, cast iron Kohler motor. I've read things both for and against switching to synthetic oil, however I'd like to get some input from this forum. Cases for and against are both appreciated as I'm trying to make a decision to stick with conventional oil or go synthetic. I have zero problems with the motor, so yes, I'm hesitant to change. However, if it will truly benefit the motor and extend its life, I will switch. I only want the best for my Cub! Thanks!

Unless you really go on a search for non synthetic oil what you will find is almost all Motor oil is some part synthetic these days. I wouldn't overthink it too much. Just use the proper weight. And viscosity as per manual.

More important to change when needed/often.
Todays oils are much better than when those engines were made.
As coop says, don't over think.
if you run syn in other equipment, then do so in the cub as it keeps oil inventory to a minimum, otherwise dino oil is good, and better than it ever was in the past. :bigthink:

Thanks fellas!

Anyone know why the 149 owner's manual discourages 10-30 oil vs 30 weight? I'm inclined to use a multiweight oil to cover all seasons since my cubs don't see lots of hours. The oil should last a few years if it's clean.

Multi viscosity oil was not invented until 1950's. I imagine it took time to catch on in small engines just like it took time for people to trust synthetics. 10-30 will not harm your engine. But I would never leave oil in anything for more than a year.

Oil
 

I use non synthetic, but add full zddp. One bottle is enough for 4 oil changes. I think zddp was removed from engine oils as it adversely affects catalyst converters. It was an important ingredient for lubricity.

I got my first Cub only a few months ago ...it's a 129...after getting involved like the OP and asking around I got a lot of differing advice...detergent...non-detergent, synthetic.....non-synthetic....I wound up using SAE30 Shell Rotella and it seems to be fine....as it is intended for Diesels, hence no cat converter to get ruined I believe it still contains the Zinc in it

Exactly what I use in all my Cubs. Occasionally use 15w40 if I'm out of 30wt but SAE 30 is the norm.

I also use ZDDP in my oil changes! (Great stuff) The only difference is I do run Royal Purple SAE 30 full synthetic in 90% of my equipment.
Like others stated before me, todays Dino oils are better than they were in prior years. Conventional Dino 30W oil would be fine, I just prefer Royal Purple.
On another note, when most of our Cub Cadets were made, gasoline was leaded, and conventional oil had a higher level of zinc (ZDDP) added to it. Lead was added to gasoline to aid in reducing wear on the valve seats, reducing engine knocking, and to help boost octane numbers. Zinc (ZDDP) was added to motor oil as a metal-on-metal anti wear agent. So on those cold morning start ups, you want a higher level of zinc (ZDDP) to be in your oil because it will help protect your piston rings, cylinder wall(s), valves, valve guides, and valve seats.
But.....fast forward, the EPA has removed lead from gasoline, and continues to lower the amount of zinc (ZDDP) that oil manufactures are allowed to add to there oils. I use VP Racing 4 cycle ethanol free fuel solely in my equipment, Royal Purple SAE 30 oil, and add zinc (ZDDP) to each oil change!
FYI, that little bottle of ZDDP does 5 Kohler engine oil changes, so it last a while!
Hope this answered your question!
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