Synthetic oil question

[Backroadguy]

Oil question , I just put 5 quarts of mobile 1 full synthetic in my 94 f150 with 210k miles. Didnt notice it was synthetic until I got home. After reading about possible leaks should I drain it and put conventional back in ? Hasn’t been driven with the new oil only started up for a few min.
Thanks in advance

 

[oilboy123]

Leave it. Not a problem.

 

[GRUMPYDUDE2]

No worries. Drive it as normal, check oil level every fill up to verify.

 

[GrumpyCat]

Once Upon A Time there was no standard or specification for oil swelling of vinyl seals. The prevailing wisdom was to use the same oil between rebuilds else risk oil leaks. The seal swells with oil then wears. When a different oil comes along that doesn't cause as much swelling the oil seal is now too small. Then along came "synthetic" Mobil-1 which had no idea it needed to swell oil seals so it pretty much reliably leaked when used in any used engine. And the "synthetic" reputation started while forgetting the exact same thing applied if changing between Havoline, Chevron, Shell, Castrol, or Mobil refined oils.

Today the SAE/API/ECMA/JASO specs stipulate oil seal swelling properties so you can use any modern oil at any time.

 

[JMJNet]

Mobil 1 is a great oil.
I would keep it in there.

When you read something, make sure you check what year the article was written.
Also, if your car is not leaking before, it will not leak because of synthetic oil.
The engine don't know and suddenly leak because you put synthetic oil. LOL.

 

[edyvw]

Oil question , I just put 5 quarts of mobile 1 full synthetic in my 94 f150 with 210k miles. Didnt notice it was synthetic until I got home. After reading about possible leaks should I drain it and put conventional back in ? Hasn’t been driven with the new oil only started up for a few min.
Thanks in advance

I would buy a bulletproof vest and helmet while draining.

You are good man. The leaks are 70's thing.

 

[CharBaby]

I may be saying this incorrectly but here goes.
Many, but not all synthetic oils are Hydro processed mineral/conventional oils(GROUP III).
There is still the(GROUP IV) PAO(polyalphaolefin) including some(but not all) of Mobil 1 oils. And there are Ester Synthetic oils(GROUP V) as in the past.

Many of the modern synthetic oils are known as Hydro cracked, ISODEWAXING(?) and new today there is GTL(gas to liquid). These processes alter the chain molecules in the conventional oil to rival synthetic oil as we know/knew them. Thus, the API allowing the processed oils to be labeled as “ Full Synthetic”(GROUP III).
So in your regard/concern there is less chance, if any, of those 1970s leaking issues with old(er) engines as there were 40-50 years ago. And, most engines are built with better gasket.

Again, I’m not sure if I said this correctly but others will correct my statement and add to it. If this isn't confusing enough!

 

[JohnnyJohnson]

Seriously if it leaks it was about to leak anyway!

 

[RDY4WAR]

Oil question , I just put 5 quarts of mobile 1 full synthetic in my 94 f150 with 210k miles. Didnt notice it was synthetic until I got home. After reading about possible leaks should I drain it and put conventional back in ? Hasn’t been driven with the new oil only started up for a few min.
Thanks in advance

That is a myth. Synthetic oils do not cause seal leaks.

There was an isolated incident in the 1970s where the potential for seal leaks was noted when using very high amounts (almost exclusively) of a specific synthetic base oil called poly-alpha-olefin (PAO). It was quickly remedied, they lived and learned. Most common synthetic oils today don't contain any PAO at all (and haven't for a long time), much less high amounts of it. The only ones that do contain high amounts of PAO are in the boutique realm, and a ton of R&D goes into those oils to offset that issue to the point that many actually prevent leaks better than common API oils.

Imagine someone stating that all Ford vehicles are junk because Ford issued a TSB about a steering column squeal back in 1972. That's what this is. It's beyond asinine. This keeps getting circulated not because people are worried about seal leaks, but because some people just like to hate anything related to synthetics.

There's more myths and misinformation out there than factual information. (sadly) You see it everywhere with synthetics being "too slippery" (myth) or "lower viscosity" (myth) or "will destroy old engines" (myth) and so on. This is a big part of why this forum exists is to correct this mess.

 

[barkingspider]

I would leave it

 

[Kira]

You've been using conventional oil in it for 30 years; correctly buying it and installing it.
What made you pick up the wrong oil?

I errantly grabbed an AGM battery recently because they changed the labeling.
The battery didn't have AGM in huge letters on it, so I assumed it was lead-acid.
I've noticed house brand conventional oils with revised, more "techie" looking labels.

 

[GrumpyCat]

I may be saying this incorrectly but here goes.
Many, but not all synthetic oils are Hydro processed mineral/conventional oils(GROUP III).
There is still the(GROUP IV) PAO(polyalphaolefin) including some(but not all) of Mobil 1 oils. And there are Ester Synthetic oils(GROUP V) as in the past.

Many of the modern synthetic oils are known as Hydro cracked, ISODEWAXING(?) and new today there is GTL(gas to liquid). These processes alter the chain molecules in the conventional oil to rival synthetic oil as we know/knew them. Thus, the API allowing the processed oils to be labeled as “ Full Synthetic”(GROUP III).
So in your regard/concern there is less chance, if any, of those 1970s leaking issues with old(er) engines as there were 40-50 years ago. And, most engines are built with better gasket.

Again, I’m not sure if I said this correctly but others will correct my statement and add to it. If this isn't confusing enough!

You are over-thinking it.

The problem was nobody bothered to design for seal swelling properties so the problem existed changing between refined oils same as changing to a synthetic oil.

Today's oils are designed for uniform seal swelling properties.

 

[Auto tech]

Let it be

 

[Hohn]

Oil question , I just put 5 quarts of mobile 1 full synthetic in my 94 f150 with 210k miles. Didnt notice it was synthetic until I got home. After reading about possible leaks should I drain it and put conventional back in ? Hasn’t been driven with the new oil only started up for a few min.
Thanks in advance

This is akin to going home from the doctor after they tell you your heart needs better care and asking your wife if you should throw out the olive garden salad and eat stale french fries off a minivan floor instead.