slo5oh Posted April 4, 2005 Share Posted April 4, 2005 Don't want to start a "my motor oil is better..." discussion, but here's my history: bought '98 2.5RS with about 50k on the odo. Changed oil from junk dealer put in to redline 5-30wt (this was over 3 years ago... and I swear it was 5-50wt, but I don't see that as an option now). She got the subie notorious piston slap when cold. I lived with it for a couple weeks until I swapped out to 5-30wt Mobil 1. No more piston slap. Changed oil every 10k up to now. No piston slap. At 120k I changed to Mobile 1 10-30 (thinking older engine, thicker oil...) Piston slap is back! My car is in the shop right now but I'm about 1k from another oil change and I already have a 5qt jug of Mobile 1 5-30 just waiting in the garage. ** edit to add ** Ran Mobil 1 0-30 "racing?" oil for 1 or 2 oil changes. Walmart clearance for $1 each Qt so I bought all (about) 20. No piston slap with it either... that's what got me started thinking about this. ** edit end ** I've read A LOT about the subie piston slap problem (on this site... p.s. thanks)... I'm seriously thinking the problem is caused by thicker oil. That's reverse from EVERYTHING I have read, I know! but bear with me... I've got piston slap on only 2 of my several oil changes. The recent one was thicker Mobil 1, the first was Redline and I swear I read somewhere that redline runs thicker than advertised. When my car comes back in (probably) 2 weeks I'll do the 1k in a week or 2 and then I'll know for sure. I guess this was not really addressed as a question, but my question is if anyone has seen the same thing I am theorizing. Quote Link to comment Share on other sites More sharing options...
Snowman Posted April 4, 2005 Share Posted April 4, 2005 I would believe that thinner oil would help with the piston slap issue. It should flow better upon startup. I believe it was Setright that developed piston slap issues after running Redline for a very short time. Quote Link to comment Share on other sites More sharing options...
cabron Posted April 4, 2005 Share Posted April 4, 2005 I would believe that thinner oil would help with the piston slap issue. It should flow better upon startup. I believe it was Setright that developed piston slap issues after running Redline for a very short time. I have a 01 legacy GT limited; with 120,000 Km. 3 weeks ago put Mobil1 5W-30. Piston slap still there. Lasts about 2-5 minutes until engine comes up to normal operating temp. I have used synthetic's in all cars I own. My engines last well over 300,000km. I use Mobil 1 because; its seems improve the longevity of the engine, and somewhat improves gas milage. Quote Link to comment Share on other sites More sharing options...
slo5oh Posted April 5, 2005 Author Share Posted April 5, 2005 I have a 01 legacy GT limited; with 120,000 Km. 3 weeks ago put Mobil1 5W-30. Piston slap still there. Lasts about 2-5 minutes until engine comes up to normal operating temp. I have used synthetic's in all cars I own. My engines last well over 300,000km. I use Mobil 1 because; its seems improve the longevity of the engine, and somewhat improves gas milage. Your piston slap is there even at idle? I only get it when the car is cold and I drive. It only happens for me at about 2k to 2500 rpm mostly when I let off the gas pedal as the RPMs are dropping back down (my car's an auto). Quote Link to comment Share on other sites More sharing options...
cabron Posted April 6, 2005 Share Posted April 6, 2005 Your piston slap is there even at idle? I only get it when the car is cold and I drive. It only happens for me at about 2k to 2500 rpm mostly when I let off the gas pedal as the RPMs are dropping back down (my car's an auto). My think its piston slap. Slight ticking sound at idle when the engine is cold. After the car warms up....no noise what so ever. Maybe its valve tick??? Quote Link to comment Share on other sites More sharing options...
Snowman Posted April 6, 2005 Share Posted April 6, 2005 Could be. Quote Link to comment Share on other sites More sharing options...
friendly_jacek Posted April 6, 2005 Share Posted April 6, 2005 OK, You have to realize that the viscosity difference between 5w30, 10w30, or 0w30 is great at -30 or so but not that great above 0-30C. Furthermore, some 0w30 oils are THICKER at room temp and/or working temp that your 10W30 mobil1 (low 30 weight). Syntec 0W30 being the best example (almost 40 weight). If I remember correctly, 5W30 mobil1 is also slightly thicker that 10W30 mobil1 at working temp (100C, 212F). (Edit: not true, checked, no difference whatsoever) So much for your generalization... Edit: This is from mobil website: viscosities in cst at 40C/100C 0W30 56/10.3 5W30 56/10.0 10W30 62/10.0 to compare, german syntec (aka SLX) 0W30 is 12.2 at 100C. Unfortunately, there is little data published for viscosities at the everage US "cold start" temps circa 0C/32F. So, use you ear... Quote Link to comment Share on other sites More sharing options...
slo5oh Posted April 6, 2005 Author Share Posted April 6, 2005 Thanks, I guess I'm looking for real world experience with different oil weights in these cars. It seems to me that when I run a higher temp (thicker? maybe, maybe not) oil like redline or the mobil 1 10-30 in my car right now I've experienced the piston slap. It does sound exactly like valve train noise... I know the sound quite well from roller rockers on my mustang that were not on tight enough. But even this noise should not come and go with the difference of 5-30 or 10-30 wt oil... I'm just grasping at straws here I guess. As soon as I get my car back I'm going to change back to the 5-30 and I'll bet $$ my noise goes away. OK,You have to realize that the viscosity difference between 5w30, 10w30, or 0w30 is great at -30 or so but not that great above 0-30C. Furthermore, some 0w30 oils are THICKER at room temp and/or working temp that your 10W30 mobil1 (low 30 weight). Syntec 0W30 being the best example (almost 40 weight). If I remember correctly, 5W30 mobil1 is also slightly thicker that 10W30 mobil1 at working temp (100C, 212F). (Edit: not true, checked, no difference whatsoever) So much for your generalization... Edit: This is from mobil website: viscosities in cst at 40C/100C 0W30 56/10.3 5W30 56/10.0 10W30 62/10.0 to compare, german syntec (aka SLX) 0W30 is 12.2 at 100C. Unfortunately, there is little data published for viscosities at the everage US "cold start" temps circa 0C/32F. So, use you ear... Quote Link to comment Share on other sites More sharing options...
Setright Posted April 6, 2005 Share Posted April 6, 2005 YEah, I had never had any piston slap up to 50k miles. The I decided to try Redline 10W40...and it started. Drained the oil after about 100 miles. No diet of Mobil 1, 0W-40 or 5W-50 has been able to cure it. Slo5oh, I think you're climate may explain why you get less slap. Quote Link to comment Share on other sites More sharing options...
cookie Posted April 6, 2005 Share Posted April 6, 2005 When I go up to the mountains with my car and it gets a really cold start the slap is far worse. I have not tried it yet with the 15-50 but I don't expect a lot of difference on a cold start. Right now my slap is way down as soon as the oil circulates in 10-15 seconds. I can still hear it if I get out of the car and open the hood. It is just muffled enough to not be audible inside the car with my tired rock and roll ears. The nice part is I don't hear it at all in the later day starts. I think I am a bit confused as these do not seem to be consistant results that we get. Of course you are running a 2.2 in Denmark and I am running an old 2.5 in San Mateo. I don't quite understand why slo and I don't have similar results as he seems to be just across the Bay. My car is probably quite a bit more worn though. It seem like if you get an oil that works for you it might be good to stick with it. Quote Link to comment Share on other sites More sharing options...
99obw Posted April 6, 2005 Share Posted April 6, 2005 Thanks, I guess I'm looking for real world experience with different oil weights in these cars. Oils I remember using in the EJ25 over the last 180k miles. Mobil 1 5w-30 10.0cSt Mobil 1 10w-30 10.0cSt Pennzoil 10w-30 10.4cSt Pennzoil 5w-30 10.5cSt Amsoil ASL 5w-30 11.6cSt Amsoil ATM 10w-30 11.9cSt German Castrol Syntec 0w-30 12.1cSt Amsoil AFL 5w-40 14.5cSt Chevron Supreme 10w-40 14.8cSt As far as engine noise, I would say that the Amsoil 10w-30 is probably the thinnest I could endorse in hindsight. The 40 weights definately have an advantage in the noise department IMHO. If you want to try a thick oil, try the Chevron Supreme, an excellent oil that's inexpensive, and thick. If you want to try a thick oil with a high viscosity index, perhaps you could try Rotella T 5w-40, around $3 a quart last I knew. I guess so far no one has proven whether it's kinematic viscosity and/or viscosity index that seems to quiet the boxers. You can also browse around this thread... http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=009433 Quote Link to comment Share on other sites More sharing options...
Setright Posted April 7, 2005 Share Posted April 7, 2005 That's affirmative, Cookie! Stick with what keeps your partcular engine happy. I wish I lived in a year-round warm climate :-( Quote Link to comment Share on other sites More sharing options...
cookie Posted April 7, 2005 Share Posted April 7, 2005 is olive oil. Quote Link to comment Share on other sites More sharing options...
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