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stu76
07-22-2009, 01:35 PM
hi chaps.

need some advice asap.
i am going to do a oil and filter change on my subaru shortly.my scooby has done 150,000 miles and going well.
i am not sure which engine oil to use as i have been told so many different lines, some say use 10w 40 semi syn ,others say use fully synthetic only, some say fully syn not really needed or warrented, please can anyone help me on this what engine oil to use, my subaru is a 97/98 year r reg.

thankyou to all.
stu

Bassman
09-12-2009, 01:00 AM
Hey Stu,

While I am not innately familiar with Subarus yet, I have a lot of experience with other vehicles. With as many miles as you indicate your "scooby" has accumulated, I'd be hesitant to switch completely to synthetic. Even the slightly thicker synthetics (10W - 30) will tend to have a thinner overall viscosity and may not offer the best protection if engine clearances (pistons to cylinder walls, crank journals / bearings etc.) have increased.

Stay with a good, known brand, multi-viscosity old unless you are certain that your engine and valve train clearances are minimal enough to support the use of the synthetic oil. Subaru recommends that one follow the service specifications regarding oil changes - - don't not exceed 7,500 miles in normal service between oil changes or more than 3,750 miles for rough service (e.g., lots of stop and go driving or operation in dirty conditions). This includes using synthetics.

ericams
12-01-2009, 02:21 AM
in your 97/98 sub you should use 5-w30 reg engine oil. That being said for high mileage engines like the sub. you can switch to 10-w30 or 10-w40 reg oil. If you have not been using fuel sythetic oil do not waste money switching now. The biggest thing is to do regular oil and filter changes and your basic tune ups. We have seen these motors go 300,000 miles before needing a top end rebuild with regular oil changes. Now then to debunk the synthetic oil myth, sythetic oil is just that it is chemically made from ultra clean non petroleum chemicals or as most people say man made. It contains no raw crude in its make up. As where regular oil is just a well refined petroleum crude that is cleaned, and processed with other chemicals to make it pass the numerous specifications like SAE(Society of Automotive Engineers) API(American Petroleum Institute) and ILSAC(International Lubrication Standardization and Approval Committee)
The fact is if an oil passes the SAE or what your used to seeing (10-w30) it is approved to run at that viscosity.

The proplem with oils today is not what the have in them but what is left out because of the EPA. ZDDP or Zinc dithiophosphate is the additive that keeps parts like you camshaft and valve adjusters from wearing. The problem is the Zinc is murder on your catalitic converter. So to get away from the Zinc car manufacturers had to switch exclusively to roller rockers and harder more exotic materiels for cam followers.
Now everyone with a new engine is happy but wait what about us guys who like the old subaru's and vw's and god forbid a chevy or ford. well we have to be smart enough to go and buy the zinc additive and put it in our own oil. Well that is enough ranting and raving about the good ole' days. If you ever have any other questions on engine oils or anything else engine related please call or email me.

thanks