roberth944 Posted August 13, 2007 Share Posted August 13, 2007 I was at Willow this weekend and heard the dreaded sound of a rod knock. I tore the motor down on Sunday to find #3 rod bearing spun. I was running 10/40 mobil 1 and it seemed really thin on draining it. What weight is a safe weight to run at this track with that heat out there? I'm going to install a accusump system and oil cooler before I go out again but would like a tip on oil weight and brand if you guys could help. Thanks Rob Quote Link to comment Share on other sites More sharing options...
924sowner Posted August 14, 2007 Share Posted August 14, 2007 you might think this funny but ive never had one problem running shell rotella T diesel/truck oil and the appropriate amount of lucas oil stabiliser. Quote Link to comment Share on other sites More sharing options...
n wright Posted August 14, 2007 Share Posted August 14, 2007 Too bad about the rod knock. I've run my turbo and various other 944's at WSIR for years in the heat. Always used Mobil 1 15 or 20W 50 and have been fine. Of course, I've always had an external cooler. Either a 951 original or slightly larger aftermarket model. I'm no oil chemist but I know what has worked for me. BTW I have a 951 cooler if you need one. Neal http://www.944specracing.com Quote Link to comment Share on other sites More sharing options...
Utah944 Posted August 14, 2007 Share Posted August 14, 2007 I second the Rotella T. I run it in the heat of Pueblo 95+ degrees and several 100 degree days in Utah. Quote Link to comment Share on other sites More sharing options...
JamesWilson Posted August 14, 2007 Share Posted August 14, 2007 The M1 0w-40 is a very very thin 40-wt, nearly a middle 30-wt according to the spec sheets. M1 5w-30 is actually "thicker" than their 10w-30 per the specs. Different oils behave differently. I would go no thinner than the 15w-50 M1 EP in the 944 engines, guys like Tim Comeau really like the LubroMoly 10w-60. Motul also makes a few 10w-50 and 10w-60 weights in their racing oils that are excellent as well. Good luck! Quote Link to comment Share on other sites More sharing options...
Weston Posted August 14, 2007 Share Posted August 14, 2007 I use 20w50, and change it and the filter after each race weekend. On a street car, changing your oil too often would be counter-productive, but our race cars get it hot enough to do some damage to it. I prefer the Valvolene VR1 racing oil because it appears to maintain oil pressure a little better than other oils of the same weight when racing in hot weather. It was either Castrol or regular Valvolene that I used at La Junta in June and I saw a bit of pressure drop when the car got hot (about 3/4 on the coolant temperature gauge), but I switched to Valvolene VR1 for the July Pueblo event and the oil pressure didn't drop as much even though it was 20 degrees hotter outside and my cooling system was overheating badly (24 year old radiator that got some overspray when the car was repainted; I have a good 951 radiator to install this week). We have 6 new 944-spec cars in our region this season, and 4 of them developed a rod knock the first time they raced in hot weather, so it's really a good idea to spend the $60 and put in new rod bearings ahead of time, but oil still plays a huge part. I know that of the first 2 of them, one had thinner oil (10w40) and the other had been run with contaminated oil (it had an anti-freeze/oil milkshake when purchased), and they both had cooling issues on top of it; I'm not sure about the last 2 though. I'm one of the 2 cars that hasn't had a problem yet, and I use fresh 20w50. I don't know how good the rod bearings were when I bought the car though, so I will be replacing them soon... I just don't have time to do it before our next event. IMO, these cars really should have external oil coolers for racing... If you keep your coolant temps low enough, you may not *need* one due to the stock oil cooler, but it's still some good insurance. Chuck said he got his from DART Auto for a good price. I'll be buying one for myself some time after our Hastings event... Quote Link to comment Share on other sites More sharing options...
pixrken Posted August 14, 2007 Share Posted August 14, 2007 Robert, Sorry to hear about the #3 rod bearing. We use 20w50 in NorCal. Thunderhill can get 100+ during the summer. We're so paranoid about loosing the #2, #3 bearings that if we open the engine enough to change out the rod bearings we also cross drill the crankshaft and install a oil pan baffle as extra insurance. Five of our cars have oil coolers also. Two with the sandwiched plate style fitting and three with the turbo style oil cooler block off plate. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted August 18, 2007 Share Posted August 18, 2007 Hot weather puts extra stress on the rods. In most all race engines you should at least replace the rod bearings. Original rod bearings with 100k+ miles on them will allow for larger clearnaces. The problem is hot oil gets thin and can't support these large clearances. Result is a spun rod. Best thing is to actually replace the main bearings too as they feed the rods. As for oil weight I run 20w50 Amsoil Series 2000 racing oil. It stands up well to the rigours of racing even in over 100F temps. I also run cross drilled crank, baffled oil pan, 951 oil cooler and check the oil level before each track session. I never overfil, but always keep it full. Quote Link to comment Share on other sites More sharing options...
roberth944 Posted August 18, 2007 Author Share Posted August 18, 2007 who can cross drill the crank for me? I've tried to find someone but have not? I'm in So Cal. Quote Link to comment Share on other sites More sharing options...
Tim Comeau Posted August 20, 2007 Share Posted August 20, 2007 Motor Works in National City (San Diego area) does machine work. 619.233.8875 I run Liqui-Moly 10W-60 racing oil, with no external oil cooler or accusump or anything else special. Start fresh and your system should work fine. Quote Link to comment Share on other sites More sharing options...
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