tuffluck

iTrader: (4)

my '00 Z has 35,000 miles on the odo. i got the car with 33,000 miles, and i changed the oil shortly thereafter. i know that the previous owner used 5w30 conventional oil, but i never knew what type of oil he used. anyway, i didn't have time to dispute the issue with myself, because i had to get the oil changed and then get out of town quickly, so i just went with what i ran on my old car - conventional 5w30 pennzoil.

now i'm hearing that synthetic is the way to go, and so i've decided to *pretty soon* put in synthetic mobil 1 5w30 with a k&n oil filter. i have a few questions:

is the thing about changing from convential oil to synthetic oil causing leaks in the ls1 a myth? or a fact?

after i change the oil to synthetic for the very first time, how long should i run it until i change it? since there will be slight remains of conventional oil, i should probably run it a short amount of miles so that i can drain it quickly and start again with more synthetic than not, right? or do i just put that synthetic oil in the motor and go for 6000 miles like everyone else running mobil 1 synthetic does? thanks!

Kev98Ta

iTrader: (4)

You can go from coventional to synthetic and be fine. Going from synthetic to conventional and youll have problems. As for the 2nd part of your question im really not sure. I can tell you that when i bought my car with a little less miles than yours and i made the switch to synthetic, i just change it every 3000 or 3 months.

Patman

You can safely put in synthetics and immediately run 6000 miles if you want. I wouldn't go too much further than this on the first run with synthetic only because it will still be mixed with conventional, so it slightly shortens it's life. Although at the same time, when my sister bought her 99 Civic a couple years ago, I switched it over to Mobil 1 and immediately she went 8000 miles on that oil. I had it analyzed and it looked like it could've easily gone much much longer.

But just to be safe I usually recommend people don't push it beyond 6k on the first interval. After that you can go longer but I don't recommend going beyond 6k without having an oil analysis done to confirm it's safety.

skunk50

wait, synthetics just doesn't lose its vicousity as fast but if you keep it in there for 6000 miles, then it's got 3000 miles worth of extra dirt compared to changing the conv. oil at 3000 miles. synthetics doesn't stay cleaner any longer than conv. oil.

and i don't see why you can't switch to conv. oil if you've been running synth oil. it's when you've got high miles using conv. oil, and the normal wear and tear causes little nooks & crannies that get sealed up by caked up gunk mixed with conv. oil.....and when you put in synthetics, it will eventually clean out that gunk and causes leaks & blowbys.

i put synthetics in my faster Mustang because i don't drive it much and when i do, it gets driven hard....so the synthetic would have higher tolerance towards protecting the motor... but in my daily driver LS1, i use conv. oil because it doesn't justify the cost since i change it every 3k miles. i'd rather have cleaner oil than keeping synthetics in there for 6k miles since i drive in dusty, rush hour traffic. but i'm sure that synthetics will protect the motor more if were to race often and keep it in the high RPMs constantly, but i don't...it's a stock A4 convert.

TeeKay

I've posted this on several boards, so I'm only going to say this once and let the rest of you hash it out. Change to synthetic if you have a healthy engine and go for the maximum interval from the gitgo!

Here's the reason: I changed from conventional (dino) oil at about 15,000 miles in my daily driver (304 FWHP 3800 six, shifts @ 6400 rpm). I used Royal Purple (similar to Mobil1) because I was convinced by published dyno tests. I also changed the trans to synthetic (RP) ATF. The combination ran .1 faster a week later at the track under virtually the same conditions. My gas milage rose 4%. I drive in all kinds of conditions, dusty, hot, high-speed interstate (100 mph+), stop-and-go city, and track. I changed the first time at 10,000 mi (!), analyzed and there was NO degradation! I could have gone 20,000 miles! Now I change oil and filter every 6 months regardless of the mileage. With that improvement, and fewer oil changes, I save about $170 per year. The performance is much more important to me than the money, but the savings are a plus.

This is just my opinion, and my experience with a highly modded car. Take it FWIW. HAND (have a nice day).

demonspeed

iTrader: (7)

I switched to Royal Purple 10w30 in my 93 Mustang when it had 77K miles. It had a slight leak at the rear main around 95K miles. Wheither or not the oil was the cause of that, I haven't a clue. I ran it with K&N oil filters and still changed it every 3K miles

I switched to Mobil 1 5w30 in my Camaro at 90K miles. I'm using an AC filter at the moment, but will go with the K&N (out of stock when I changed the oil). I plan on going 5K miles between changes.

I just switched my girlfriends 03 Grand Am GT to Mobil 1 with a K&N filter this afternoon. It almost has 11K miles... since August, so it gets ran a lot. I also plan on going 5K miles between changes.

I am worried about something with the Grand Am though. Hopefully Patman can help me. For whatever stupid reason, I didn't even bother to do the first oil change in the Grand Am until it had 4500 miles. So I had run on the stock 5w30 and AC filter for this amount of time. Could it have caused any damage or harm? Will this effect the engine in the long run? I just keep worrying about this. I mean, we'll probably be getting a new car in a couple years, but still, it's bothering me. Any advice?

tuffluck

iTrader: (4)

i'm not an oil expert, but from what i do know, i don't think that'll be an issue. as long as you are not flooring the car all the time, and getting the oil extremely hot, i don't think an extra 1000 miles is going to make a damn bit of difference. and even if you are flooring it, i still don't think it's going to be a big deal. just my .02

demonspeed

iTrader: (7)

Well, I did make a few passes down the track on the original oil I'm sure there's nothing that will go wrong now that i'm pretty much religous about taking care of the car. I don't know why I bother though, it's not like it's going to be worth any more money come trade in time.

skunk50

6 MONTHS??? but how does synthetic oil stay cleaner than conventional oil with the same filter? i mean dirt is dirt.

Patman

Running the original factory fill out to 4500 miles like that should not significantly affect the overall picture here, I wouldn't worry about it. You probably got a bit more engine wear, however not enough to shorten it's life by a huge amount. Keep in mind that there are many people out there who use crappy oil and only change it every 5-7k and still manage to get over 150k on their engines somehow.

Patman

If you're using a good air filter (not K&N!) then you shouldn't have too much dirt getting through into the engine. My wife's Honda only showed 4ppm of silicon (dirt) in a 5000 mile interval last year using the Fram air filter. With such an extremely low number it's obvious that it's not going to hurt anything.

demonspeed

iTrader: (7)

Thanks Like I said though, we'll probably be getting rid of it before it would be of any concern.

TeeKay

Quote:
Originally Posted by TeeKay
I drive in all kinds of conditions, dusty, hot, high-speed interstate (100 mph+), stop-and-go city, and track. I changed the first time at 10,000 mi (!), analyzed and there was NO degradation! I could have gone 20,000 miles! Now I change oil and filter every 6 months regardless of the mileage. With that improvement, and fewer oil changes, I save about $170 per year. The performance is much more important to me than the money, but the savings are a plus.


Quote: Skunk50
6 MONTHS??? but how does synthetic oil stay cleaner than conventional oil with the same filter? i mean dirt is dirt.

Most "dirt" in engine oil comes from the breakdown of the oil not from the dust outside the engine. If the oil doesn't breakdown, then the oil doesn't get "dirty". When you're driving in dusty conditions, the filter you change is the AIR filter, not the OIL filter. HTH

Patman

FWIW, if you change your air filter too often, you allow more dirt into your oil. A dirty air filter traps more dirt than a clean one.

skunk50

hmmm, this does make sense.

how and where do you guys bring the used oil to have tested?

Patman

http://www.blackstone-labs.com/index.html

skunk50

hey thanks for the link Patman. i'm gonna put synthetics in for 6k miles and see what the analysis say. it's well worth it then (to me) if i can go 6k and not worry about dirt in the oil. not having to crawl under the car every 3k is well worth it right there. plus 3-4 rwhp too right? and added engine protection.