OCI for Amsoil Dominator 15w50

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May 31, 2009
Vestal, NY
Hello everyone! I run a dirt modified on circle tracks in NY and PA. I'm new to this class, but I've been involved in racing my entire life. What I am also new to is synthetic racing oil. In the past, I've always run either Kendall or Valvoline 20w50 racing oil. We always changed oil at least every other week. I'm not sure if this was necessary, but that's what we always did. Now I am running Amsoil's Dominator 15w50. It seems natural that you wouldn't have to change synthetics as often as dino oil, but I can't find any actual recommendation. I have heard of people running entire seasons on synthetic, but I don't know if this is a good practice.

Really, I don't think I am being that hard on the oil. The engine is a Chevy 358 with a roller cam. Per the rules, I am only running 6000 rpms. I've only run it once and got the water temp up to 180; I do not have an oil temp gauge. The former owner said he didn't get it much warmer than that. It has a circle track oil pan with an approximately 7 qt sump. The filter is a Wix 51069R. It is run on VP 110 leaded racing fuel through a Holley 2 barrel carb. I don't know that much about this engine, as I bought it as is and haven't had it apart. On a typical race night, I run about 35 laps between practice, heats, and features. This is at tracks from 1/4 to 3/8 mile. I am currently debating if I'm going to stick to one night a week or move to two.

So what do you all think? I'm sure a UOA is the best answer, but I am new to this stuff and not sure about everything involved. What is a typical turnaround for a test? Since I am kind of week to week, I can't really wait a month for test results.

Thanks for any help.
If it is well broken in, I would say go 3 to 4 weeks, but do at least one UOA. Of course if you have any overheating (sounds unlikely) or other issues drain and refill.
I've raced on circle tracks, but never raced on dirt tracks so YMMV. I would recommend setting your OCI based upon the amount of fuel dilution you experience as the season progresses. (You want to make sure that your oil sees at least 210F during the race to vaporize any water condensation or raw fuel.) I would send in an oil sample one a month if you're aiming to run all season with the same oil (which is possible with a solid engine running synthetic oil).

Also, I would get an oil temperature gauge and watch it to determine what oil temps you are seeing during the race. If you're going over the the 260F reading in the pan, you want to stay with a synthetic oil product whatever you chose. As a safety precaution, always pre-heat your oil to at least 185F before a race. (Redline Oil recommended that I not push my engine until their oil was at least 210F in the pan for best results.)

BTW I've found that running any type of 50 weight oil in a small block Chevy gives up some HP across the torque band. Your water temperature sound extremely low to me to be using 50 weight; however, I understand that dirt tracing tends to clog radiator fins to the point the car can overheat towards the end of a race. There should be more HP available by switching to a lower weight oil, but only a dyno will tell.

Good luck Racing!
I'm running AMSOIL Dominator 10w30 on my road course car. It's a stock 350 Chevy LT1 FI with headers. I've already done 3 days of racing on it and plan on doing a UOA following my next weekend to determine how far I can go with it. I'll probably switch to AMSOIL 10w40 AMO though.

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