The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

Re: The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

I know a guy that bought a Craftsman push mower in 1989, has NEVER changed the oil, just keeps adding to this day. Personally I think he should be horse whipped!!!!!

Re: The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

I can not believe the amount of time that is put into some of these posts:confused2: Oil has improved exponentially over the years.

I did learn something from Bert though-

Before the engine is laid up over winter.
Synthetic or non synthetic, sitting in the sump for 4 months going nowhere and gravity will do its dirty work and deposit all of the heavy nasties that were suspended in the oil into the lower bush and all of the lighter acidic nasties will float to the top doing their best to turn your engine into scrap metal.
This efect is worse in synthetics than std oils because they are freer draining

Re: The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

Improved is loaded word as is best.
What has happened over the years is we have learned how to take crude that is totally unsuitable for use as lubricating oil and turn it into 1st class lubricating oils.
We have learned how to fortify light oil so it behaves like heavy oil at operating temperatures thus extending the oil supply and reducing the costs.
However 5w30 will never be as good as strait 30 in some applications for no other reason that what was done to make it 30 will get undone over time
Where as 30 will remain 30 for so long as it does not get cooked.
Racing has led to developing thinner oils that can take a lot more punishment and tougher thinner oils has allowed for much tighter clearences.
Engine technology has gone so far than now days the viscious drag of the oil becomes significant.
This is important in racing where every Hp is so precious a lot of top class drives shove a supository up their clacker before a race to evacuate their bowel and reduce weight by a pound or two.
Motorcyclists from the kick start days are very aware of this as it is significantly harder to kick your bike running heavy summer oils than it is to kick it with light winter oils.
The 13 Hp M20 has the same top speed running any oil but the 65 Hp Yammie lost 25 kph when running on heavy summer oil.
The exact same engine used for 3 different applications will require 3 different oils.
Snow blowers need to be able to start at very low temperatures so they need a light oil to be able to start, mowers get started on hot days & used in hot situations thus a heavier oil is required while generators need to span an even wider range of temperatures and be stable for very long running periods and to transfer heat a lot better than a snow blower.
However none of this is relevant to lawn mowers and doubly so to Briggs & Kohler engines which are so under stressed that the oil drag is inconsequential .
The prime factor in the design of a mower engine is CHEAP and cheap = loose.
You can get 40Hp out of a 500cc intek but the only original parts used will be the cases & crank and the engine will end up costing a couple of grand.
For a couple of grand most now days expect a complete mower along with a bikini clad cutie pie to bring you cold drinks.

Thus mower engines are crude rude & unsofisticated, for now with wide open running clearences that are too big for thin oils to maintain metal separation.

However the one thing that has never changed is an engine produces by-products that contaminate the oil which need to be removed and the most effective way of removing them is to change the oil.
Synthetics are a lot more stable and the addative packages remain in a useful condition for a longer period, but the contaminants still concentrate in the oil thus the oil still needs to be changed.
The frequency of the oil changes is determined by the design parrameters of the engine, not the oil.

A good example of this is a friend who had an A65 BSA that had a worn main bush and was bleeding off oil pressure.
It had done near 20,000 miles when he got it cheap so was 2/3 through the design life of the bottom end.
Rhett ran this bike on deisel oil which he got cheap from work.
He changed the oil every time he used the bike.
He sold that bike 35 years latter with over 80,000 miles on the clock, still on the same bottom end that he bought it with.
The new owner had thrown a rod within a year.

SO the BEST oil for any engine, is the oil that has just been changed.
Prior to becoming a small engine mechanic , I ran hire car business & courier company.
Everything ran on recycled 20w 50 which meant I could buy it in 44's for 1/6 the price of retail packs of virgin oil.
The Mitsubishi vans were fine, the Yamahas used a bit more than they should and the Rollers gobbled oil at an alarming rate.
However the hire cars got oil changes ever 3 months which was 1/2 the time internvals & about 1/20 the mileage intervals recommended.
The vans got monthly oil changes and the motorcycles were weekly or fortnightly depending upon the rider.
We had no oil related problems with any vehicle for near 30 years.

Re: The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

bertsmobile1 said:

SO the BEST oil for any engine, is the oil that has just been changed.

Click to expand...

I'm going to Agree Here bertsmobile1!

Re: The Reason I think Synthetic Oil is Best for 4-Cycle Mower Engines. "Who Agrees?"

bertsmobile1 wrote: “However the one thing that has never changed is an engine produces by-products that contaminate the oil which need to be removed and the most effective way of removing them is to change the oil”.

Just finished changing the oil on my mowers, and my mechanic son used engine flush which seems to work as the oil is the same colour as what went in after some minimal use. This I suppose is beneficial, especially with small mowers with no oil filter? I use mineral based Honda oil in engines (10w-30), and full synthetic oil in the hydrostatic drives (15w-50) as per owner manuals.