Frequency of oil changes

C

craig bryant

Well-known member
I know that the joke with British cars is that you never have to change the oil, you just have to keep adding it, but what is the consensus of how often the oil in race motors should be changed? After every race.....?...every other race....?...every third race? All opinions are appreciated. Thanks.

Craig Bryant
 
Oil testing is relatively inexpensive. Take a sample and send it out for testing after a weekend. If it needs to be changed each event this will tell you. It will also give you a good idea on the health of your engine.
 
I have been told that the red line race oil needs to be changed every 2-3 weekends - that the additives break down and it begins to foam more after that. OR, as soon as possible if the oil gets up over 270.
 
Does the answer to this question have anything to do with how much oil there is? Running a dry sump with 3+ gallons of the stuff I would think that you would be able to get an extra weekend or two out of it compared to a car that had the stock sump with an accusump.

I know when ran Mazdas back in the '80's we would change the oil every weekend but with the 1200 I think I changed it every 5 races or so.
 
James Rogerson":2lr63w5m said:
I change all mine after every race weekend.
Click to expand...
Why? The "cheap insurance" mantra? Why not after each day? each session? I'm just trying to understand why people choose certain intervals. Bobby gives some insight to his choice. I change after every other race weekend, because my engine builder (J. Prather) tells me to do so. When I ran my Sprite with a dry-sump, I would go more races and add as I burned oil. I always heard back that the rod bearings looked good when it was time for a rebuild.

I think I may take the advice and have some oil tested - I have never done that.
 
My understanding, as a Mechanical engineer, is that the lubricating property of oil never wears out: it only becomes contaminated (chemically and mechanically) and loses additive package effectiveness (anti foam, anti corrosion).

In an HP 948 Sprite, I ran Mobile 1, and both an Oberg filter (40 micron)and a cartridge filter (10 micron). I checked the Oberg after every session to see what was happening inside the engine, and I changed the cartridge filter after every weekend, 'cause I didn't know what was in there.

I would change oil after every engine rebuild (using petroleum oil for break-in), every season, and if it darkened appreciably (high temperature operation or blowby contamination). Probably averaged 3-4 weekends per oil change. I always changed the oil filter with new oil.

I follow the same practice on my street vehicles. I'll change the oil filter only at 4-5000 miles if the oil is still clear, and change both oil and filter when the oil darkens appreciably.

Your mileage may vary.

RJS
 
Bobby, RJ and Rob have the best answers and perspective, because they know why or under what conditions to change the oil.

Food for thought:

Why do the oil companies recommend 3,000 mile intervals? But, the car manufacturers recommend 6,000 miles between oil changes?

Do they have pit stops to change oil in 500 mile races, 6, 12 or 24 hour races?

Is your oil capacity 4 quarts or 3 gallons?

Do you change the oil as you are at the end of your season, and putting the car away for the winter?
Do you change your oil when you have 3 or 4 races coming up in the next 2 months, and you have fresh oil in the engine since last weeks race?

Has your oil temp been over 270 degrees?

Has your oil pressure light has been flickering due to fluctuating oil pressure? Have you been keeping track of your oil filter conditions, how frequently?

Have your old oil tested, as you are changing it send in a sample of the old oil. You may be pleased with the result$.

I believe in testing for education on how to treat the motor.

But, I have also had good connecting rods pass magnaflux testing. And had one failed magnificently 10 laps later....
 
I believe all Caterpillar dealers offer the service. I think they ship it off to a lab for the full analysis.
 
RonInSD":1wpmvm3l said:
I believe all Caterpillar dealers offer the service.
Click to expand...
CP = Caterpillar Prepared?



PLEASE NOTE: After class competition, track may require minor cleaning and/or total resurfacing :shock:
 
According to Red Line Synthetic Oil (I just hung up the phone with Dave in the tech department) three hundred degrees of oil temperature is no problem for any of their engine oils. He stated that once you get above three hundred twenty degrees oil temperature then you start running into problems with seals getting soft.

I change the oil on my Baby Grand every other race weekend. That car uses a Yamaha R1 powerplant.

YMMV.
cheers
dave parker
 
Bill Trainer asked:

"Where do you send oil in for testing? Thx"

Benz Oil in Milwaukee, WI tests hydraulic oil for mechanical and chemical contamination. Could probably do engine oil, except for additive package. With shipping, takes a week or more. Don't know costs.

Hydraulic oil users are facing 20-100 GALLON replacement, so more cost effective for them.

Greg?

RJS
 
Blackstone labs is a place I used years ago.. http://www.blackstone-labs.com/
there are many others now.

I change the oil in my car twice a year just to pretend I'm trying not to kill it. (once the 130k mile stock engine dies, I have more reason to build a proper engine..)
 
A few years ago when this came up, Kevin Allen quoted a Chrysler or Mobil engineer (from Viper endurance racing) as saying that Mobil One, running under 300F (IIRC), was good for x many racing hours, where x was large enough that I decided to change it only once per racing season....

Regarding engine oil analysis for race car oil - has anyone actually done this and used a lab that was familiar with race engine oil applications?
 
When you send a sample to most of these places, they ask what the oil is, is used for, what it came in, how many miles/hours are on it, etc etc etc.
They will look at your sample and compare it to the specs from the same oil when new. I'm not sure if they actually test the new samples themselves or just get specs/analysis from the manufacturer. given what they test for and list, they probably have to test it themselves.

I just happened to go here since I've heard of the site, and voila- front page has a site visit and description on how Blackstone does their testing. Interesting reading.
http://www.bobistheoilguy.com/
 
This same questions has been asked many times on this forum and I have always been amazed at the replys. I personally have run many, 24 hr & 12 hr races and we never changed the oil during the event. So what's the diff ?
 
Years ago I remember seeing a picture of the back of a GT5 car with oil dripping out of the tailpipe and a a bumper sticker that said "motor oil is motor oil". Some Brit cars have self changing oil while some Jap cars with weak components inadvertently make large oil drains in the side of the block, no matter how often you change the oil. Seriously though, very useful info is obtained from oil analysis. You should contact your oil mfg. first and ask what firm they suggest you use though. Each oil co has their own preferred analysis firm that is familiar with their oil's specific formula and therefore knows what additives to expect to find and can tell you how the heat and wear and metals in your engine are affecting that particular motor oil. Not all test companies have the specific additive list for each oil company as they are very protective of that info.
Regards,
Keith
 
You must log in or register to reply here.
Back
Top