Is synthetic and conventional oil interchangeable?
I bought synthetic, meant to buy conventional. I really don’t wanna deal with the always long line at the return desk. Can I just use the synthetic even if I use conventional usually?
The engine is a 3mz-fe in a Toyota Sienna.
February 19, 2020, 07:14 PM
wreckdiver
I hope so, 'cause I've done it. These days I only use synthetic.
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"Once abolish the God, and the Government becomes the God." --- G.K. Chesterton
February 19, 2020, 07:18 PM
arfmel
Me too. No problems have resulted.
February 19, 2020, 07:19 PM
PowerSurge
Yes.
——————————————— The fool hath said in his heart, There is no God. Psalm 14:1
February 19, 2020, 07:21 PM
Skins2881
You can switch back and forth with no harm. The only time I wouldn't is if you car specifies to use synthetic (obviously not the case here).
Jesse
Sic Semper Tyrannis
February 19, 2020, 07:22 PM
thumperfbc
Great, thanks!
February 19, 2020, 07:42 PM
sigcrazy7
Synthetic is superior in every way, except for new engine break-in. I don't know why you'd want to go back to mineral oil.
Demand not that events should happen as you wish; but wish them to happen as they do happen, and you will go on well. -Epictetus
February 19, 2020, 08:18 PM
comet24
Yes.
You can even mix synthetic and conventional oil.
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Because in the end, you won’t remember the time you spent working in the office or mowing your lawn. Climb that goddamn mountain. Jack Kerouac
February 19, 2020, 08:19 PM
Gene Hillman
Also do not mix the two. For example, don't add a quart of conventional oil to an engine full of synthetic or vice versa. Make sure you change the filter when you do the oil change.
Addition to original above post- I stand corrected. My post was based on incorrect information from many years ago. Mixing is now considered ok. Sorry!This message has been edited. Last edited by: Gene Hillman,
February 19, 2020, 08:45 PM
Shifferbrains
quote:
Originally posted by thumperfbc: I bought synthetic, meant to buy conventional. I really don’t wanna deal with the always long line at the return desk. Can I just use the synthetic even if I use conventional usually?
The engine is a 3mz-fe in a Toyota Sienna.
You are good Mike, no issues at all.
February 19, 2020, 09:16 PM
comet24
quote:
Originally posted by Gene Hillman: Also do not mix the two. For example, don't add a quart of conventional oil to an engine full of synthetic or vice versa. Make sure you change the filter when you do the oil change.
Why?
They are both engine oil. No issue mixing them. The only issue would be your wasting money on the advantages of synthetic by adding conventional. Other than that it will do no damage to your engine.
_____________________________________
Because in the end, you won’t remember the time you spent working in the office or mowing your lawn. Climb that goddamn mountain. Jack Kerouac
February 19, 2020, 09:19 PM
Skins2881
quote:
Originally posted by comet24:
quote:
Originally posted by Gene Hillman: Also do not mix the two. For example, don't add a quart of conventional oil to an engine full of synthetic or vice versa. Make sure you change the filter when you do the oil change.
Why?
They are both engine oil. No issue mixing them. The only issue would be your wasting money on the advantages of synthetic by adding conventional. Other than that it will do no damage to your engine.
Yeah why? Wouldn't that be the same as using syn blend?
Jesse
Sic Semper Tyrannis
February 19, 2020, 10:04 PM
tatortodd
quote:
Originally posted by Skins2881:
quote:
Originally posted by comet24:
quote:
Originally posted by Gene Hillman: Also do not mix the two. For example, don't add a quart of conventional oil to an engine full of synthetic or vice versa. Make sure you change the filter when you do the oil change.
Why?
They are both engine oil. No issue mixing them. The only issue would be your wasting money on the advantages of synthetic by adding conventional. Other than that it will do no damage to your engine.
Yeah why? Wouldn't that be the same as using syn blend?
No. To make it the same you have to shake it vigorously while jumping on one foot, spinning counterclockwise, and singing It's Raining Men.
Trust me, I'm in oil & gas
Ego is the anesthesia that deadens the pain of stupidity
DISCLAIMER: These are the author's own personal views and do not represent the views of the author's employer.
February 19, 2020, 11:53 PM
jimmy123x
Yes, it's interchangeable. Synthetic could cause leaking seals/gaskets to leak more while you're using synthetic on very high mileage vehicles. Other than that, it's generally superior to mineral oil in every way, but depending on your change interval might not benefit you at all.
February 20, 2020, 02:17 AM
SIP2000GLO
You're fine. I've done it many times when I had my Toyota Tacoma. I used Mobil 1 synthetic and changed the oil at around 7K miles intervals.
After 4-5 changes of synthetic oil, I switched to Walmart Supertech conventional oil and ran for 1K miles to flush the engine, then back to Mobile synthetic again. Never experienced any leakage due to switching different oils.
When I sold my Toyota Tacoma it had 368K miles on the odometer and the engine still ran fine with no issues whatsoever. It also did not eat oil for an engine with such high mileage.
I will continue to do the same with all my current vehicles.
February 20, 2020, 05:14 AM
sourdough44
I agree with above, most of us don’t plan on mixing.
The only reason would be if whatever engine had requirements for oil that wasn’t met, synthetic, or the viscosity.
February 20, 2020, 05:33 AM
Dreamerx4
I would disagree actually with switching back and forth.
If you have been using conventional oil for a long time, and have higher mileage, and switch to synthetic, you may see leaks appear.
If you have been using synthetic oil for a long time, and have high mileage, and switch to conventional, I have had leaks STOP.
This is my experience. What are the long term affects of low mileage, swapping back and forth??? maybe marginal... BUT, I am sharing what I have experienced personally.
My daughters car, 2003 Camry, was adding lucas stop leak to the synthetic oil as it was loosing a fair amount. Switched to conventional, SAME weight, and leaks have all but stopped.
I personally would stay with synthetic at all times, unless you have high mileage and leaks, or are burning it, then go conventional and cheap:-)
Cause a leak, NO. But if you already have one, which many high mileage engines do (usually a seep that most owners don't even notice), the synthetic will leak more. Also with old gaskets in 1990's cars that weren't formulated for them, such as the GM truck engines of that era, yes they will cause leaks with the type of rubber they initially used for gaskets......keep in mind I'm talking 1990's GM engines or older (and some others). These gaskets do NOT like the additives in Synthetic oil. While this is a possibility in some vehicles, switching back to conventional usually turns the leaks back to normal. Aside from my own personal experience with this when I used to turn wrenches, there are many articles that support it.
