Synthetic oil myth or fact?

[diesel lover]

My 1997 Ford F150 has 130,000 miles on it. I had a few people talk me into changing over to a synthetic oil for the engine due to the Sub zero temperatures this winter. I made a compromise and went with maxlife synthetic blend oil. Around 4500 miles =/- into the oil I then repaired my front cover leak on my truck. At this point I put Conventional oil back into my truck. Now my truck seems to be using more oil than it was. It was a quart low 2 or three days ago, I added a quart of oil and checked it to find it 1/2 quart low still... Puzzled I checked around the underside of the engine and the rear main seal area is wet with oil.

I have heard that if an engine was broke in on synthetic oil (has 75,000 or 100,xxx miles with it) than you should STAY with that oil and also if it has 100,000 miles with conventional oil than you should stay with that as well. I have read that switching from conventional to synthetic oil then back to conventional can cause a temporally noisy engine. Well, after changing from a synthetic blend back to conventional oil I had a lot of engine noise from a lifter on the passenger side of my engine. My engine has pushrods. I removed the oil pump and inspected/ measured it while replacing the front main cover seal, and when installing the oil pump I had primed the oil pump and also the oil filter to insure fast oil prime and flow.
Upon engine startup I had instant oil pressure but one of the lifters was just going crazy! This continued for lets say 3 minutes. A few days after that the lifter was still making more noise than it usually did. Now after 2,500 miles the lifters are slightly noisy but sound exactly like they did when I bought the truck a year ago.

So, Myths or facts??
1. Does switching from conv oil to synthetic cause an engine to start using more oil? I have heard this is due to the synthetic oil "slipping" between the gaskets and seals
2. Does switching from conv to synt and back to conventional again cause an engine to become noisy/ have noisy engine parts?
3. Are there other issues known as well? I advise everyone that ask me NOT to mix them unless you do not have a choice. Never mix synthetic and conv engine oil or gear oil as it can cause issues. Even if they do mix ok its not a regular practice that should be preformed.

You are all open to your own beliefs as I have mine. From my schooling and my experience I use whatever Engine oil that is on sale and carrys the API oil donut. If the oil does not carry the donut than it is snake oil and has never been tested in an engine before. Lately menards has 4 or 5 quarts of Coastal engine oil for $8.50! That's low cost. I belive it is better to change the oil or fluid on a regular schedule than worry about spending time only using one brand or more expensive oil.

 

[art]

Good oil is a cheap investment and everyone seems to have ideas as to what a good oil is. Working with other people engines for the last 45 years I've seen a lot.
I do recommend to stay one way or the other on oil not switching back and forth. I do recommend using a good oil and filter no matter what!

We have diesels that are in excess of ten thousand hours in tractors with no rebuilds. Just had a rebuild in our shop from a customer that was done somewhere else do to cost. It's going to cost more now from not having it done right the first time!

It has been said that synthetic on an older engine will find any potential leak it can and I think your engine proved it!

The lifters tell me that the engine either had cheap oil or it didn't get changed enough!!!!
Might be interesting to look at the build-up on the inside of the engine, that often tells a lot!

 

[Tig]

My observations, opinions and reasonable hearsay:
1. Does switching from conv oil to synthetic cause an engine to start using more oil? I have heard this is due to the synthetic oil "slipping" between the gaskets and seals

Hearsay; Synth will clean gunk from worn seals causing them to leak.

2. Does switching from conv to synt and back to conventional again cause an engine to become noisy/ have noisy engine parts?

Observation: Synth makes my normally noisy engines engines run quiet. I have one vehicle which is near end of life. I put conventional oil in and I can hear the difference.

3. Are there other issues known as well? I advise everyone that ask me NOT to mix them unless you do not have a choice. Never mix synthetic and conv engine oil or gear oil as it can cause issues. Even if they do mix ok its not a regular practice that should be preformed.

Opinion: mixing brands of oil was always a no no. 35 years ago in auto shop class we were told mixing oils could cause acidity as the different detergents combine.

Observation: I do tend to have a favourite brand, but any oil is better than dirty or no oil. I have mixed as required and have not noticed any ill effects.
I run Mobil1 in my favourite engines. I'm very happy with the way they run and sound.
.
So there you have it, my experience. The only fact might be the no oil comment.
My vehicles are all higher mileage than your truck. I am a long time synth user and have no leaks.

 

[buickanddeere]

Synthetic oil is for use in extreme cold , extreme heat or under extreme load.
If the machine doesn't fit those , it isn't needed.
Probably just a better detergent package that removed crud the other oil left behind.
While I don't have any use for snake oil . There are specific additives that will swell gaskets and seals . Which may reduce or stop leakage.
Then again with that many miles and years. Why he surprised if it starts leaking oil at some point. ? Synthetic or not.

 

[Looking4new]

I will be leaving Shell dino oil in my 175,000 mile Jeep. I will also be putting Rotella T-6 Synthetic into my Kioti.
The company I work for puts synthetic oil in everything except the engine of my 2001 Freightliner w/C15 cat. The tranny and both rear ends get synthetic.

 

[pmsmechanic]

I've had some experience using a dino oil in summer and a synthetic in winter. I have two Dodge trucks both with cummins engines. One thing I immediately noticed is when I shut off the engines with dyno oil in them the fan belt gives a short squeal as the engine rolls to a stop. If I use synthetic this doesn't happen which I take as an indication of less internal friction with synthetic oil. I've also noticed on my 98 Dodge that the synthetic oil does not turn black nearly as fast as it did with dyno oil. The local John Deere service manager tells me that if I use John Deere synthetic oil with their filter on a John Deere tractor I can increase oil change intervals by 50%. For me this works out great as I then only have to do one oil change per year. So a few years ago I made a decision. I'm not a fan of storing and using numerous different kinds of oil so most of my vehicles now use JD 0W-40. The only exceptions are our TDI Jetta and my quad. Yes it costs me a bit more but I don't have to be so fussy on oil change intervals. Also noticed that the cummins gets a bit better mileage (1-1.5) with synthetic.

 

[Soundguy]

i have a 99 f450 that has had syn from day 1.

I have a 99 f350 that ran the first 160k of it's life as dino oil. it's now a bit over 200k and has been on syn since 160k.

no engine oil leaks ( tranny don't count.. ) no odd usage. etc.

I went to syn on those diesels due to some severe driving and operating conditions , heat , turbo.. etc.

 

[murphy1244]

My 01 F250 Came with Mobil 1 From Ford.

 

[Baby Grand]

Flat tappets or roller lifters?
One of my tuner buds says that the removal of the zinc additive from engine oils is hard on flat tappets.
He's usually a pretty reliable source.

 

[DeereMann]

I used to work at Mobil Oil in Industrial Lubricants, so you can call me biased - but I saw witnessed test results with cleaner engines, less wear, easier starts, less vaporizing & varnishing, etc.

Furthermore, as pmsmechanic says, you don't have to be overly concerned with precise oil change intervals as the oil itself doesn't degrade and add to the contaminant carrying load. Of course, you can't extend your OCI's to the maximum touted by the oil makers without routine used oil analysis, so for us noncommercial types changing at the 'Maintenance 2' schedule for our equipment is easily achievable without concern.

Is the extra cost worth it? Probably not, except in extreme cold & heat as B&D says. But I like the piece of mind and OCI flexibility depending on weather & my schedule.

Anyway, synthetic oil superior performance is real, no doubt. Some GDI car engines will void warranty without it now, due to the engine oil also being used as hydraulic fluid for VVT valves, etc. That system has to stay clean without varnish or deposits.

Hope this helps with your decision.