I've always heard that once you use synthetic, that you really shouldn't go back, because the seals expand a bit with the synthetic, wear somewhat, and then when you go back to dino, you shrink and leak. Is there any truth to this? Horror stories, success stories?

Here'* my train of thought. Nine months out of the year, it'* between 30 and 90 degrees up here, and I run 10w30 dino without guilt. The past two weeks though, it'* hovered between 0 and 20, and I don't even like to imagine how thick my oil is on startup. So I was thinking that maybe I could run some synthetic, or a 5w30, for those three months, and switch back to the cheap stuff for the remainder of the year.

I know, I know... In a perfect world, I'd be running mobil 1 all of the time. I just can't justify the cost. Maybe I could justify a blend, like the Valvoline durablend or whatever.

Also, I've always used 10w30. It'* what the manual recommends, if I recall correctly. Is that what you all use too? I see that Haynes says that I can also use 5w30, but I read somewhere once that the bigger the difference between the numbers (5 and 30, in this case), the more non-oil stuff is in the oil, which isn't good. So I don't know. Thoughts, anyone?

If it makes you feel confident. My car had Mobil one from 30k-120k. She had dino from 120k-150k. Leaks? My lower intake gasket leaked like hell, to the point where I had to tear the engine down. Are they related? Beats me.. Just food for thought..


-justin

My books say 10W-30 is ok for service above freezing (32F) but the recommended oil is 5W-30 for all temperatures.

Since I live in Florida, I use 10W-30 which is also recommended full time for my "L" 3800 but 5W-30 should be no more expensive.

The major issue with dino oils is that over time the long-chain polymer additives which make oil a multiweight break down and with a 5W-30 you are left with about a straight 20 weight oil. My experience is that this process takes between 3 and 5 thousand miles on my cars (I run them cooler than stock with 180F thermostats and a cooling system that keep it there).

On other cars that is when I would notice a slight drop in oil pressure that would come back with an oil change (too many Jaguars in my yout make me sensitive to oil pressure).

So I use a good (Castrol or Valvoline depending on what is on sale) 10W-30 is almost everything and chainge oil and filter at about 3000 mile intervals.

Lately I have thinking more about synthetics because of the gallon of oil that must be disposed of after every change.

You could say you're helping gas prices, the environment, etc....

I haven't heard many problems with the switch back to Dino. But i haven't seen effects of different types of oil on seals. Most of the leakage from switching TO synthetic is because it cleans so much better. That'* why oil turns black, it'* actually cleaning at the same time.

keep your 10W30 ... follow padgetts change advice (as everyone should anyways) ... but if your really worried about your engine oil being to thick on cold weather starts (the few you may get) just get a block heater or an inline water heater

I lived in places that saw -30 Celcius or lower( well below 0F for you non metric types) for atleast 4 months out of the year... all I ever used was 10W30 Dino oil and an inline water heater ( the inline water heater also gives heat faster in the interior )

block heaters and oil pan heater work too... but the inline water heater will warm AND circulate the warmed water throught the whole block .. instead of just heating 1 area and hoping the heat goes through the rest of the engine.

temperature here hovered around 0F for about a week, my old 200K mile LG3 showed no problems with starting and getting oil pressure , with no heating aid, on a fresh oil change, I'm running 10W30 Castrol High mileage Dino oil.

Yeah, I'm probably just paranoid.

I wish I had an oil gauge, instead of just a dummy light. The light goes off right away after starting.

The heaters are a good idea, but my problem would be mostly at work. I work 2nd shift, so I get out at midnight (really really cold), and the car has been sitting for 8 hours. At home, I have an attached (but uninsulated) garage which generally doesn't get colder than 20-30F.

I'll probably just stay with what'* been working for the past 16 years.

0w30 synthetic was run (well... we've accidentally bought it, what to do with it now that doesn't include going back to Wal-Mart and exchanging it?) for one change in me motor.

No issues. 10w30 dino before and after that.

there shouoldn't be a problem going to synthetic then back to conventional. (why does everyone call it Dino? is it because its old style?) Anyways, what I've noticed synthetic does is just intensify current oil problems your enigne might have, especially leaks. I put in synthetic blend once and it leaked out so incredibly fast it was almost funny, whereas my usual 10w-30 takes over a month to leak a quart (usually about 2 months).

Anyways its not a problem to switch to 5w-30 for a while then switch back to 10w-30. Or you could change in steps: go to a syn. blend on your next change, then to a full syn. then when you wanna go back to conventional, go through syn blend then back to conventional. That is if you are so afraid that the switch from syn to conv. and back could be harmful ( i wouldn't think itd do any bad).


but as for my personal recommendation to you. Just go 5w-30 on your next oil change. i'd stick to conventional too just cuz its worked all these years.

It comes from the ground, ie real oil (as opposed to synthetic), which comes from dinosaurs/ancient life and stuff, therefore "dino"? That'* what I always thought...