Summit Racing has a full line of sythentic oils on their website (and in their catalog). As far as I know, you can change over at any time. It is important that you follow any instructions from the oil manufacturer about changing over. I know some guys that go so far as to change over to silicone brake fluid too. I know to switch to silicone brake fluid, you need to bleed the system thoroughly. Then bleed it with silicone fluid. The good thing about silicone brake fluid, is that it doesn't absorb moisture out of the air, so it prevents your steel brake lines from rusting from the inside out.
There really isn't anything to "convert" to start using synthetic lubricants. The only thing that Amsoil (they are a major player in synthetic technology)recommends is to run their engine cleaner in older engines before making the swap to synthetics.
The only problem you may ahve is that in an engine that has a bunch of miles, and the seals are getting questionable, you may have leak problems. This is partly due to the extra cleaning capabilities of synthetics and partly due to their being "slipperier" than petroleum oils. In the first case they will clean out gunkt hat is sitting in a gasket and may open a leak that was not ther earlier. In the second they will pass throguh seal clearances that are small enough to contain petroleum oils.
The benefits of synthetics are extended drain intervals (up to 25,000 miles/one year), better lubrication and increased temperature tolerance.
I'm running Amsoil in all my stuff, doing yearly changes. That's in both the truck engines and all the air cooled mowing equipment. The air cooled engines run hot anyhow, but the Amsoil is not cooked and blackened after almost 300 hours of run time. I'm also using their synthetic tranny fluid in my plow pumps, it doesn't thicken in the cold and seems to hold viscosity as the pump heats up.
I think you can get more information from the Amsoil website, www.Amsoil.com
When it comes to oil weights... READ YOUR OWNERS MANUAL!!! For example, in my '96 Z71 5.7L, I run 5W-30 Amsoil YEAR ROUND. Gm recommends 5W-30 in most of their engines. Some of the clearances in the engine are too tight for 10W-40 or 20W-50. You may feel that 5W-30 is too thin for summer driving, but that's not necessarily the case.
The good thing about synthetics is that they never lose their lubricating properties... so I've been told. They do however absorb dirt and gunk. That's why they need to be changed. I'm running the good Amsoil in my truck. It's supposed to last 25,000 miles. There is no way I'm waiting that long to change my oil. I plan on changing the filter at 6,000 and then changing the oil at 12,000. I've been told the reall winner is synthetic in the transmission. That's my next project. I just have to figure out how I'm going to get all the old fluid out of the trans.
I use Amsoil too,the important thing to remember is that no one should be running it 25,000 miles or one year without the bypass filtration.The bypass filter,and oil sampling is what allows the extended drain intervals,it will filter out 99% of the particles at 3 microns and larger,without it your oil loads up with filings in the 1-10 micron size,and without draining them out they build up to unsafe levels,since you oil filter cant filter them out,then your oil becomes a nice grinding compound.The full flow factory filters cannot catch all the fine particles and flow enough oil for the engine.The oil is still good,but it gets so contaminated with small debris that it will eat your engine.The bypass filter will pay for itself if you run a lot of miles,it is also nice to not have to change your oil,and still have it clean as a whistle after 10000 miles.It adds about 1quart of oil capacity to the system too,which helps it run cooler.For anyone that doesnt know,the bypass filter filters only about 10% of the oil flowing thru the main filter at a time,but it filters it down to 1 micron,so its like new oil coming out of the filter and going back to the crankcase,it takes about 3 minutes ruuning down the road to completely filter all the oil thru the bypass filter.Big rigs regularly run over 100K miles on there amsoil using these bypass filters,and there oil samples come back great,so long as a good air filter seal is mantained.
so in searching over at lawnsite and here at plowsite i found this thread.
i made the switch to synthetics in my trucks, but i was wondering about intervals. now i know calculating can get tricky when your plowing (miles vs. hours) but relative to regular oil what am i looking at? should it be changed half as often? as often? the 25000 miles quoted above seems insane, but i dont know. was hoping to have some new opinions on the matter added to this thread.
and was going to go synthetic in the trannys too. any guides there? i was thinking at the start and end of the plow seasons to be safe, but is that overkill?