5w-20 or 5w-30? doesn't matter, right?

mostsmooth

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Hi all,
95 gt, H/C/I mods
I needed some oil, for some reason I bought and added some Mobil1 Full synthetic 5w-20 and apparently, 5w-30 is what I am supposed to use.
As far as I know, this isn't a problem at all, but, I don't know much.
So, this isn't a problem at all, or do I need to stop driving the car immediately until I change the oil, or is it somewhere in between?
I live in new jersey in case it matters and it's winter here now.

thanks
 
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mostsmooth

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and while im asking probably stupid questions, i happen to have a jug of un-opened Mobil 1 syn 5w-30 that has been sitting in my garage for possibly up to 17 years. this is garbage now, right?
 

jozsefsz

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I don't think a top-up with 5w20 is going to make much of a difference. The old 302 has sloppier tolerances than modern engines, but probably still burns less oil than a 2021 Chevy. I think the stock recommended weight was actually 10w30, but 5w30's cool for the winter. 5w20 is getting a bit thin so it might burn off some - this also depends how many miles and what condition your engine is in. Personally I wouldn't worry about it too much, but I would change to the recommended weight next time.

The 17 year old stuff, in a sealed container, is probably just fine too. I wouldn't pour it into anything I cared about though (just my opinion), I'd use it up in an old lawn mower or my Mustang II. :) Just kidding love my II.
 
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General karthief

wonder how much it would cost to ship you a pair
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17 years? I'd toss it, well not literally but I wouldn't use it.
5w-20 is ok but I would swap it for 10-30 by summer time, that's just me.
 

mostsmooth

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thanks guys

i can use 10w-30 year round right? the temperature rarely if ever gets down to 0, and if it does, i can just drive my other car
 

revhead347

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A top off of any particular weight will be fine. Yes, 10W-30 is good year round. I mean, scientifically, the 17 year old bottle should be fine, but I wouldn't use it.

Kurt
 
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7991LXnSHO

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and while im asking probably stupid questions, i happen to have a jug of un-opened Mobil 1 syn 5w-30 that has been sitting in my garage for possibly up to 17 years. this is garbage now, right?
So how long was the crude oil in the ground first? (about 6000 years or much, much longer depending on how you think the world was created?)
17 years in a sealed plastic container is not long enough to deteriorate the oil. I do not think it affects the additives a bit either at normal garage temperatures. I found a stash of the right service grade oil for flat tappet cams at grandpa’s shop. There was no separation, it looked and smelled like new, although I did not taste test it.
Eight years later I have almost enough for one oil change before I start using VR-1 Valvoline. I wish I had found another two cases.
Now the Fram and Puralator filters went into the trash. Surface rust and questions about how brittle the glue made that choice easy.
 

revhead347

Apparently my ex-husband made that mistake.
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So how long was the crude oil in the ground first? (about 6000 years or much, much longer depending on how you think the world was created?)
It's Mobil 1 syn, so it was never actually in the ground. It's made from whale fat and :poo:.

Kurt
 

7991LXnSHO

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It's Mobil 1 syn, so it was never actually in the ground. It's made from whale fat and :poo:.

Kurt
Funny. This oil is more stable than anything for animal consumption that might turn stale or get nasty while out of the freezer.
Synthetic means they purified the base and made even more stable and considstant molecules out of it. The base might have been natural gas. I know an oil industry insider I can ask to find out for sure if you are curious. It’s not advertised, but it’s not something too secret.
If the viscosity and service rating both fit, it should be far better than any store brand oil ever will be.
 
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7991LXnSHO

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I heard back from the industry insider expert. After 2-4 years, the additives could precipitate. Shaken up, it will be good as new. He shakes up oil bottles before opening to be sure before opening.
 
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Neuron

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Not like tires then. Luckily don't have to worry about it, but I will make sure I get the newest stock. With 10K oil changes I ain't taking any chances!