SubyRS25

I know most of you guys have turbo wrx's and legacy's. So this question doesn't really pertain to you guys unless you know anything about the old school RS. From what I am reading, your oil changing schedules are different than the 98-01 RS. I am reading that from your cars having a turbo that the oil heats up and breaks down faster and you need to change it more often. I still have my old school 99 Impreza RS Stock. I keep reading in the manual that you are supposed to change the oil at 3750 under severe conditions. I usually do a-lot of short trips under 5 miles in stop and go traffic in the suburbs of New Jersey with Both Cold and Hot Humid weather. So they constitute that as being severe. The car has 75k miles on it. I have been using Mobil 1 synthetic 10w30 on it since i got the car with 30k miles on it. Do I just keep changing it at 3-4k miles like I have been doing or do you think the oil can last longer? also is that 3750 mile change for conventional oil or synthetic? Any advice on the matter would help. Thanks.

loccomoffo

Oil breaks down (oxdizes) at a faster rate as you increase its operating temp. Synthetic oil is used in more sever heat conditions ie turbo or raced NA engine. Because synthetic oil resists oxidation it can be changed at double the dino oil's recommended interval under normal driving conditions. The reason you change the oil is because oxidation causes the oil to thicken up thus increasing its viscosity and its ability to support loads. The second reason you change oil is because it accumulates particulates from combustion and engine wear. For this reason personally I think that using normal dino oil is better, it's half the price, you change it at 7000km, and youre engine oil is cleaner more often with less particulates which cause engine wear.

secondglance

iTrader: (1)

Suby I am in Jersey too, and as far as your oil question.... if you go synthetic it usually lasts longer. however you have to look for oil consumption..... it is more expensive, but it last longer and it coats your engine.... I actually had a car with a small oil leak continue to run on no oil when it was using full synthetic... Not that I recommend trying ti! LOL.... my advice is to try it... If you dont like it you can always go back to conventional oil

SubyRS25

Thanks for the info guys.. Appreciate it...

loccomoffo

SubyRS25, sorry bout my rambling, to answer your original question 3750 mile change out is for dino oil, synthetic can last twice as long

Don't worry too much about changing it out early with your driving habits, oils have a safety factor built in like anything else. As we say down under, She'll be right

Secondglance, don't rely on the oil "coating" your engine, it's more marketing hype than anything and whatever coating it does is meant to protect your engine at initial start up before journal bearings build up enough speed hydrodynamic lubrication and before other parts get sprayed with oil.

awdstcroix

I have 13,823 miles on my 06 and the last time I changed my oil was at 9,000+ miles. I just changed it yesterday with Royal Purple 5w-30 aswel las my gear oil with GL-5 75w-90 Royal Purple aswell. Some say that this is really early to change my gear oil but I like to keep my things running at top notch ..and whe n iremoved the drain plug Ihad some charcoal grey sludge on the magnet plug...yeah nothing very big or grainy like sand but thats all the break in fine metals that where on the gears..glad I changed it now she shifts even better. I thin knext to REDLINE shock proof I'm gona run Royal purple in my engine and tranny and rear diffs..why cause there products are proven.

secondglance

iTrader: (1)

definitely not relying on loccomoffo just and example of the difference in the coating properties.... i definitely would not but my car would have been toast on conventionl

not12listen

at current, Mobil 1 says that their oil can still clean and be useful in an engine upto 5000 miles or so, but that you should still change the filter element at regular intervals.

in all honesty, once the oil is dark or black, its time to change it, regardless of mileage.

myself, i am lazy. i change my oil and filter every 2500 miles. and yes, i also use Mobil 1 10w30 full synthetic. even when i was using Castrol GTX 10w30 natural, still 2500 miles is the most i go before a full change.

----

one of my uncles is a mechanic, and has been for 20+ years. years ago, Mobil 1 used to claim 15,000 miles, then it dropped to 7500...

loccomoffo

not12listen, why don't you just use dino oil instead seeeing you're changing out so frequently? Unless you're thrashing the car so hard that you're worried the excessive engine temp is thickening up your oil at an accelerated rate?? Would save you some $$$ too

not12listen

oh. i tend to break engines... so, while it could be argued that even the added protection of super duper oil isnt enough, i would really hate to see how short the life span of my engines would be otherwise...

but, above and beyond everything else, its peace of mind and personal choice.

wrxisthebest

iTrader: (15)

i personally use AMSOIL Racing fully synthetic oil...

and their filters lol.. sorry i am sponsored by then. i get my oil for 5$ a quart.

i change my fluids every 5,000 miles and my oil comes out slightly gray nothing major tho.

i have 113k miles and even with the turbo my oil turns out purdy in the end.