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I apologize fore yet another synthetic oil thread, I just couldn't find what I was looking for! I have a 99 ob with 94k miles and I'l about to do the changeover to synthetic (mobil 1 5w30). I'm using an oem filter and whatnot... Anyway, my question is, for a motor that's had dino oil in it it's whole life, do I need to do any kind of flush before I change completely over? Or will that take away ALL of the deposits in my engine that are actually helping to seal the pistons? Thanks for any input, I don't want to hurt my baby!
 

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don't worry abt flushing, if you've changed your oil regularly, there shouldn't be any major deposits anyway. there will be a bit of resiudual mineral-based oil, but that will be gone/diluted into oblivion after 2 oil changes or so.

what creates piston seal is not sludge but tight fit of rings against cyl walls, and this is one of the areas where synth oil most helps to reduce friction and wear. so you won't hurt baby but rather be making baby happy with switch. :) :)
 

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Actually I did about 3 hours ago! I appreciate the advice, cpt. It was kinda fun (read:cold) at 20F, but it was quick so not too bad. The car does idle and run more smoothly, so far I'm impressed! So you guys think I should change again in 3k to get the "gunk" out and then go a little longer for the next one?
 

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yeah, good plan. but i never push their claims, still usu change at abt 5K or less, cuz i tend to run engine hard.

oh, and you need to add the Crunchberry additive.... :D
 

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Just remember one thing, a lot of the people that do extended drain intervals still replace the oil filter between drains. Depending on what engine they have determines how much loss of oil when they pull the filter off, then they top it off. I have more or less found out that the oil filter is the weakest link when it comes to how long you really want to go between oil changes. Like the Cpt. said, 5k is fine for synthetics and that is right about when I change mine.

Oil filters can collapse (inside) and loose efficiency when they are all gunked up with everything they took out of the oil. That poses the biggest threat with a lot of miles between changes. The synthetic oils can sometimes got 10, 15k on them before they become a problem.

Brian
 

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Yeah frankly I don't have the chutzpah to push more than 4 or 5k, it just doesn't seem right. I figured I'd do 3k before the first one and then go to 5 after that. Assuming I keep using oem filters, you think they'll go for the 5000 without a problem?
 

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yes. Farm also makes a pricier-than-usual filter line which they tout as being designed for longer synth oil change intervals, i use em but no idea how they work. also, K&N sells oil filters which i suspect are better than cheapies but no expereince with them. since the Sub size (Farm 3593) is super common on jap vehicles, they prob make one that wd fit.
 

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What is the Sub spec on oil change interval? If you go with that and the right quality and spec of oil, how much trouble can you get into? Porsche 928 (have an 83) recommend 15k miles oil change. Many people do much more often than that. One 928 guy in trucking business did a documented set of oil tests (Delvac 1 5w-40) TO 12000 miles in one year, with samples analysed every ~3k miles. At the end it was rated as 'excellent condition , suitable for continued use' by laboratory, but he changed it because of the time interval.
jp 05 OB 5 speed
 

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I think under normal conditions Subaru says every 3750 miles. I'm not sure the time interval. But if you don't drive much like my wife, twice a year no matter what is what I do.
Her Baja just turned 7,300 miles and we bought it in July of '03. And the good thing is, just today I accepted a job at her workplace which is 8 minutes walking distance from the house. Brian
 

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05 OBW in Oz are scheduled for Oil change at ~8000mi interval, or 6 months. I wouldnt be surprised to see early muffler deaths with a lot of short runs it sounds like you are doing there.....
jp 05 OBW 5 speed
 

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"early muffler death" is also pronounced "Honey, that factory Sub replacement exhaust is SOOOOO expensive. i'm going to look around for something more economical. maybe those Cobb or Stromung or Prodrive people have something affordable....."


altho i suspect that scammer Brian's spouse is already onto that sort of BS.

Greenie, are you listening? sounds like you need to work on practicing these car mod scams now that you have de ball und chain......:D

seriously, jp, it is hard to argue with the results of microscopic oil analysis. your post makes me wonder if i shd be just changing the filter every 5 thou instead and replacing whatever synth falls out with it.
 
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