Oil Viscosity

What are the current thoughts on Oil Viscosity.

We have always used Kendall or Brad Penn Nitro 70 wt oil.

I know teams use 60 or 50 wt depending on weather and wether or not the heat the oil.

However, what is the general thought on the light weight oils like 15-40 Weight. It seems like some of the teams have switched to the lighter weight oils.

What is the Pro's and the Con's

Thanks for the input

Sincerly,

Absolute Pleasure Racing

Gary Mangiafico

 

Gary,

I was visiting with a Texaco Oil Engineer a few years back when the advent of low viscosity oils hit the racing market. He stated "An engine will produce more horsepower the thinner the lubricant up to the point of metal to metal contact. We have tested this data on the engine dyno. At that point the horsepower will drop out quickly and engine damage will result.

Nascar runs a lower viscosity oil for qualifying then a higher viscosity for racing. Many Pro Stock engines run a low viscosity oil in the "0" weight range. The visosity is a temperature, clearance and pressure relationship.

The Pro-Stocks pull into the water around 100 degrees and 140 out the other end. Running Comp engines, we got caught up in the thin oil lubricants for a time as it is so critical to have all the power you can get to qualify and race.

Running my performance jet boat on the lake, especially with N2O and running with an A/Fuel team, I have come to also respect the need for higher viscosity lubricants. In the boat, the engine has a constant load which builds more friction and heat in the lower end which thins the oil. The oil becomes thinner as temperature increase and then when the N2O is used, the bearings and pins take a major load increase causing even more heat. Bearings and valve train components last longer with a higher visosity oil up until the point of too slow a flow. One has to remember that the oil also serves as a coolant to remove heat from the bearings, valve springs, etc. as well as a the cushion between the metals.

With all that long winded statement, where does that leave us in TAD? How much power do you need versus life of your parts. If you really believe you have your tune up nuts on and you are willing to risk some parts longevity and still need more power you may consider going to a 50 wt oil or less.

What I have seen in TAD is that most folks tune up may not be to the point of taking this risk and it looks to me as if they have more of a problem keeping the bottom end together. Oil dillution is also a major consideration with a nitro engine.

For dependable performance and engine life, my observations have been during most parts of the racing year in the central and south usa that a 60 wt oil performs quite well. Even an additive such as Lucas can be used to increase the viscosity in high oil dillution engines such as A/F. If you are having excessive bearing wear or failure, increase the viscosity. If you feel comfortable with your engine wear and want to see if performance can be increased..... then lower the viscosity in small steps.

Have you looked at the oil draining out of an A/FD? This stuff goes from mollasses to yellow milk shake in five seconds..... Just be careful and use your best judgement to keep up with you bearing wear, etc.

Good Luck!

 

That http://www.bradpennracing.com/Products/racingoils.html is hard to beat. Here in Palmer Alaska race days rarely reach 75 degrees. I've run both the green Kendall 20w-50 and straight 50. After 5 rounds in a blown alky 20w 50 is pretty thin and I don't think I would use any other brand besides full synthetics like:
http://www.royalpurple.com/xpr-racing-oil-rh.html
http://www.redlineoil.com/products_motoroil.asp?categoryID=2
http://www.klotzlube.com/storeCats.asp?ci=3
http://www.torcousa.com/products/pr...ecd17105&cat=automotive racing&type=motor oil
Up in Fairbanks Alaska temperatures get as high as 95 or even 100 degrees. Back in '94 we ran 6.20's up there with a big chief head BBC in a dragster with valvoline or castrol ? 20w-50 in it and had lifter issues.I now believe the lifter problem is directly related to thin oil.

If you decide to try thin oil keep a close eye on the lifters. You can take them out and roll the roller with your finger if it's rough the needles are getting flat spots, the next thing that happens is the roller explodes! Isky RedZone lifters are available with a bushing instead of needle bearings to fix this problem. Oddy's sells them. I did not give you a link to Oddy's because the last time I went there my computer locked up and I dont want to rewrite this again.

Also; some of these full synthetic race oils "royal purple" contain a lot of moly and I think this may attribute to the needle bearings not turning and getting flat spots. It might have been penzoil 20w-50 that we were running back in '94, it contains a lot of moly also "liquid ball bearings". You can tell if oil has moly in it by the black left in the bottom of the pan.