Amsoil for stock car racing?

[BK19]

what type and viscosity oil would a guy use in say a imca stock,modified or even a hobby stock and how many races can you run it for and how many filter changes in between full oil changes

[theoilman]

Definitely, the RD Series race motor oils.

RD50, 15W-50 best in lower cost, higher clearance engines. Typical engine clearance 1.5 thousandths or even larger.

RD30, 10W-30 best in crate motor classes, typically engines that were designed for 5W-30 or 10W-30 oils originally, typical bearing clearances around 1 thousandth (though I have heard of many crate class drivers using 5W-20, but when you use an oil lighter than the designed you are definitely sacrificing protection).

RD20, 5W-20 best in higher dollar, tight very precise engines.

When you use a lighter oil you will get a little more power and possibly a little less heat - it takes less energy to pump the lighter oil. But when you do use lighter, the molecules are smaller and if the clearance is larger than designed for that viscosity it will squirt out too easily leaving you less protection and potentially higher wear.

Above links take you to pages with full oil data info and comparison tests to other popular racing oils.

[theoilman]

I will not give any specific answer, but guidelines to help you make your best choice. Every one will be different.

First, the only real way to know is to use 'Used Oil Analysis' where you take a sample of the used oil, send it to a lab and have it tested - to tell you the condition of the oil, the additives, any contaminants, all wear, and life remaining recommendations. Without using analysis it would be difficult for me to ever recommend more than twice as long as pretroleum oils. AMSOIL does have testing available through "Oil Analyizers, Inc."

Remember, most using petroleum oil change their oil every week!

Dirt or Asphalt? On dirt you will go less than on asphalt, 1/2 as long on dirt probably.

On dirt - do you ever face a 'dust bowl' race? When the water truck is broken down. After one of these, change everything including your lungs!

How long are your races (in laps)? Laps are a bigger consideration than length of track - 2 throttle cycles per lap - will be far harder on the engine and oil than a long track, say 1/2 mile or longer.

What type of air filter? If a K&N or other oil wetted gause you'll be lucky to go more than 1 or 2 weeks. These filters do a very poor job of removing small particle dust, they remove the "big birds and small children". The right air filter: the AMSOIL Nano-Fiber Air Filter will give the flow of the gause while providing 50 times better dust removal. Plus it is dry, clean it in a few minutes with a shop vac or low pressure shop air.

My personal experience: I have crew-chiefed an open wheel modified (asphalt version of IMCA) over 5 years. We ran mostly 30 lap feature races with an 8 lap heat race and 10 to 20 laps of practice/warm-up. Typically 50 to 60 performance laps every week. With oil analysis we found we could run 4 weeks, change the oil filter, run another 4 weeks, then change oil and filter. Even at the end of 8 races the analysis said the oil was "satisfactory for continued use," but the viscosity was starting to drop. Due to fuel dilution from the high compression race engine and the 2 throttle cycles every lap the viscosity had dropped 1 grade from 50 to 40 after 8 events.

[theoilman]

Definitely, the Severe Gear Family.

For asphalt circle track, 75W-90, SVG (also most all drag racing)

For dirt circle track, mostly smooth or not too much "air" time 75W-110, SVT

For dirt circle track, rough tracks and a lot of "air" time 75W-140, SVO

For monster truck, rock climbing and other extremes use the specialty race gear lubes: SAE190, SRN or SAE250, SRT

[BehindtheHead]

good post. very interesting

[BK19]

so would you have to break it in on regular oil or can you use synthetics right away

[theoilman]

Many times a professionally built motor will be run in and adequate break in on a dyno, just start out with synthetic.

A home built, crate motor, or non-dynoed engine - I usually recommend running the first event on conventional petroleum oil, and not trying to win but run mid-pack. Then change to synthetic for second event on a new engine.

Many people start with synthetic without doing any break-in. Most racers aren't concerned if the engine uses some oil - if they use 1/2 quart or up to 1 quart in an event they consider that acceptable, and never worry about break in to seat rings.