Synthetic Oil Question

No downsides to using, or switching to synthetic at any time. Synthetic costs a little more upfront, but you can safely go to 10,000 mile oil change intervals which will mean less money in the long run with no loss of protection.

 

No matter what oil you use oil gets dirty. So why would you push off your oil change with dirty synthetic oil.

 

Exactly.

For every person who has a 400k mile truck who swears by synthetic, there are probably 10 others who used whatever conventional walmart crap was on sale, and probably weren't even religious about the 5k change intervals, either.

 

Because you paid $12 a quart for it and need to feel like it was a good financial decision.

 

My '95 turns 25 years old next month. With a couple weeks of treating her to (likely) her first synthetic, she developed some seepage.

I'm pretty sure that's a downside.

 

Walmart has supertech synthetic for $15 for a 5 quart jug, their conventional was $14, seems like a no brainer. Although I of course needed another quart, and the 1 quart bottle of synthetic was 14 cents per ounce, while the conventional was 9 cents per ounce. So I guess I'll have approximately 17% conventional oil in my truck for the next oil change.





Also.








Oh nooooo not another oil thread!

 

just found a small leak on my '12 with 79,000 miles. been running mobil 1 since first oil change. i cleaned it up and tightened two bolts on the timing cover by the leak. if she still leaks i'll try the hi-mileage mobil 1.

 

you can, just get a 'high mileage' oil, it will make the seals swell up/condition them. You will have to use high mileage from that point forward though, the moment you switch back I am pretty sure the seals will go back to normal afterwards. (could be wrong but idk why you would do this). It is high mileage oil that generally confuses people when it comes to "switching back and forth".

Or you could just replace the seal.. depends on your needs, financial situation etc.

 

I switched to syn and now my head gasket leaks, coincidence? I think not!

 

In the winter I run full syn in all the vehicles including a 1996 Camry. I've found starting is easier in the -10 to -30 + range.
Never a leak issue
As one poster mentioned many oils nowadays are a blend even though it may say "conventional" on the label

 

I think conventional oil, even if a blend, has a much broader polydispersity distribution and a different set of detergents. Since synthetic has a lower average molecular weight it it does pass through seals more readily, regardless of the state of the crud that may be removed by the detergents.

This thread is a good resource for the various modes of thinking about it, thanks.

 

Would be weird to use a high mileage oil, then switch back, as if your truck is only temorarily "high mileage", lol.


I could see that if you switch to a high mileage when you don't really "need" to, that could cause the seals to swell, and actually induce an issue that didn't exist before.

Ideally, we'd always fix the actual problem (replace the leaky seals), rather than a bandaid fix like thicker oil or parking in the grass so you never see an oil spot...

 

The only risk I've heard with switching oils and tend to believe, is when your start using a high mileage oil the additives in it are designed to help swell up old seals to prevent leaks. If you stop using a high mileage blend after using one for awhile, your seals might not be very happy about that

I've been using a high mileage oil for a couple years now, truck only has 88k on it but she's 16 years old and so are the seals.

 

After all the input I’ll be using standard conventional. Figure if it ain’t broke....

Maybe when I buy that nice 2030 Tacoma I’ll go synthetic ‍♂️

 

Personally I think it’s about keeping clean oil in your engine.
It’s easy enough to look at the dipstick to see if it’s getting dark.
I change my oil every 5k with regular oil like clock work and never have an part fail
from an oil issue.

Both oils get dirty no matter so I would prefer sooner oil changes with cleaner oil
regardless if the oil will last 10k.

 

Your head gasket leaks oil?

 

yeah man right into my tranny

 

You sure it's not the valve cover?

 

rear main seal?

 

I don't have valve covers