HDMOs and track duty

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Nov 6, 2002
Mississauga / Ontario
Assuming one is dead-set on using a conventional oil in an engine, are there any possible downsides to using an HDMO fleet oil in a track/street application as opposed to regular OTC conventional motor oil? Leaving the argument: "40wt oil might be too thick", out of this query, my thinking is that HDMO fleet oils have excellent additive packages, and they tend to stay in grade much longer than their OTC conventional counterparts. As such, if a 40wt is acceptable in this hypothetical situation and oil consumption is not an issue, are there reasons why anyone should use anything BUT HDMOs, especially in track duty? -Paul [ April 27, 2003, 11:20 PM: Message edited by: Paul ]
Paul I'm new here and by far no expert but I have dug up something that may or may not be relivent. In a GM Publication titled Chevy Power ( The GM factory Hi Perf recmondations ) (1978) They recomnded to avoid oils that contain Barium or Calcium as these componets in the carbon deposits on the pistons can cause preignition.Granted that was dated info and may not be relivent today. In the forum that is dedicated to Virgin Oil Analysis, mikeyoilnut has very generously suppied several VOA's on the HDMO Fleet style oils.As I look through them they all seem to contain Calicum.And as I can find the info these HDMO's seem to have Sulfated Ash Levels in the 1.2 to 1.5 % range compared to .8 or so on the PCMO's.I have read that the high SA levels can lead to deposits on the ring package and combustion chambers that can lead to preignition. I am curious is there truth in this. In theory the HDMO's sound great but I was advised by Kendall Motor oil not to use them in my gasoline engine as the higher Detergents/Dispersants were not worth the potential problems of the higher SA numbers in my passenger car application.Great for Diesels but not optimised for gasoline use even tho they are certified for gasoline use. Has anyone eles heard that or can comment on this. Paul I have no idea what sort of track engine you are running , your static comp ratio or dynamic CR cam timing , ect but preignition or detination is bad no matter what.I am abit conserned about these oils as to weather they potentially can contribute to any of the above problems.As I stated above I really cant say for sure but hopefully others can. [ April 28, 2003, 12:10 AM: Message edited by: Calvin ]
Calvin, Wouldn't ring and piston deposits due to higher SA levels be the consequence of oil burning? Please keep in mind that in this hypothetical situation, oil consumption is not an issue. As such, no oil burning would occur. In this case, should we still be concerned about SA deposits? From what I've gathered on this site, SA deposits seem to be the only downside of 15W-40 fleet oils. But if we eliminate oil consumption, what else do they have going against them? -Paul
As to the calcium etc. deposits forming hot spots, there's every chance that they do. A guy at work runs Rimula X in everything, including an old patrol that uses more oil than petrol. His plugs are this lovely white popcorn effect. Still, at less than 7:1 compression, it doesn't constitute a problem in his car. I do agree that if the oil doesn't get consumed, then the stuff can't form significant deposits. That's why they had volatility reductions for SL oils, to reduce catalyst degradation from addtives. BTW, didn't G.M. sell the "Engine Oil Supplement", which was chock a block full of ash forming constituents ?
Yes indeed GM does produce a product called " EOS " Engine Oil Supplement.Crane Cams also has a cam break in concentrate that has high levels Zinc Dithophosphate.They both recommend that they only be used during the cam and lifter break in period and not to be used on a continous basis due to the potential deposits and preignition problems. Haveing no clue as to what type of raceing and potential oil control issues... Thin rings ,high cyl pressure , methonal based fuels , dry sump or vacuume pump use , long or short distance running the preignition was just a consern worth exploring. No judgement on these oils was being made by me as I was curious also and wondered if things have changed and this is or is not a potential problem.
The problem with deposits and cat.damage is overblown the company I used to work for used Delo 400 in everything,Semis ,ford vans including the triton engines the owners new vette.forklifts no problems with smog teste on the vans or company cars and the vans would fall apart but the motors would run good. We sometimes forget all motors must be worked hard once in a while to blow out the deposits and keep the rings free. The 15w/40 oils may be too heavy depending upon application. Probably won't hurt if the climate is not too cold.
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