Changing her engine oil to synthetic

[71CHEVYSHORTBED402]

Just some history. She blew a cork the day I was fired because the boss was a Dk. Abusive guy, they didn't need a reason and didn't, short I saw him in his office getting a lap dance. Geez, lost my Sheba two days later. On the bright side, it allowed time to tend her, and the place hired me back a month later for more $.

I was fairly green mechanically, but my buddy helped me R&R at his place and equipment, all while I sprayed parts, and an engine bay without taping stuff off 0F-30F for days☺....Actually held-up, and what a poor job That was 1993, I believe 99K on the 402, daily driver following a rough winter.

The engine rebuilder was real good, I caught him before meth took his skills away, and life literally. 40,900 on that engine today, in short I had no reason to replace it for a restoration. I used Durablend 10-40 and 20-50 with great results. Short too many leaks Come to think of it, our R&R couldn't have been that great, standard gaskets perhaps, even old Durablend will find leaks. Today's best gaskets>>>standard, and on that note, the pans take longer bolts, so ARP>>>factory bolts for the job too.

She purred with 20-50, but they changed the formula, so I found information on this website pushing Mobil-1 Full S 5-30. At your own risk, miles may vary. But here's the thing, my experience. I didn't like the way my engine felt with that oil change, and thought bummer; it is what it is, once full synthetic engine oil is used, I've heard you can never go back.

So happened this was the last oil change before the engine was put to sleep 6-7 years, for a restore, though perhaps another for a very short duration.

With the maiden start, the engine felt better than I remembered, and really, it's been changed another three times over 900 miles Today it runs the best it ever has. No leaks with the good gaskets, so far

It's just that in my experience, IMO, when you switch oils, especially to full S, run it a short while, and then change it again.

[Willshook]

Just remember that if you have a flat-tappet cam, you need 1000 - 1300 PPM ZDDP - which that oil does not have.

https://www.mobil.com/lubricants/-/m...5A6CCC91BE38D9

Synthetic oils tend to have a higher solvency - it's one of the reasons that when you tear down an engine that's had a steady diet of synthetic it's incredibly clean.

When you swap on an older engine, two things tend to happen. 1) the higher solvency tends to clean out quite a bit of gunk and a change after a few thousand miles is a good idea. 2) it sometimes cleans gunk away from marginal seals - so you hear sometimes that an engine only started to leak after synthetics; this is often the cause.

[un4gvn!]

I have a ZZ454 in my 69CST. The booklet that came with the engine said to run full synthetic oil, so I did. Ran it for years with that type of oil. Last summer I changed the oil to convential. Seemed to run the same up until Labor Day weekend. I checked the oil and it looked super thick on the dip stick. I was done for the summer and fall. I pulled the engine figuring on putting in a ZZ502 cam swap , timing chain, roller rockers and complete tear down just to check every thing out. It started leaking oil, so all new gaskets from GM Performance also. I used their gaskets because of the aluminum Heads. What I'm getting to because I change oil types is when I pulled the oil pan, the oil looked like real thick pudding. It was a pia to clean up. It was all through the engine. I had to take the whole engine apart to clean it out. So my suggestion is don't mix the oils. I'm not sure if thats what happen, but I never saw this happen in all my years of working on engines. I didn't have any engine damage. Maybe I got to it before it would happen. I installed the engine right before Christmas and it seems to run good so far. I won't really know how it runs til the weather gets warmer. Just my 2 cents.

[70STOVEBOLT]

Why would you not be able to switch back to dino oil from synthetic?

[un4gvn!]

I changed to convential from synthetic. There's always left over oil in the engine from the last oil change. My guess is when the left over synthetic mixed with the new oil something happened. I also use top name brands of oils. I'm not saying that's what happened to my oil, but it was the only thing I changed.

[71CHEVYSHORTBED402]

Originally Posted by Willshook

Just remember that if you have a flat-tappet cam, you need 1000 - 1300 PPM ZDDP - which that oil does not have.

https://www.mobil.com/lubricants/-/m...5A6CCC91BE38D9

Synthetic oils tend to have a higher solvency - it's one of the reasons that when you tear down an engine that's had a steady diet of synthetic it's incredibly clean.

When you swap on an older engine, two things tend to happen. 1) the higher solvency tends to clean out quite a bit of gunk and a change after a few thousand miles is a good idea. 2) it sometimes cleans gunk away from marginal seals - so you hear sometimes that an engine only started to leak after synthetics; this is often the cause.

That makes sense why the leaks.

There are mixed opinions ZDDP or any additive are necessary, and in some cases can reduce performance. I'm no expert, it's just what I read. Personally, I don't use an additive; it has a flat tappet cam that looks great after 40K on old Durablend.

[GSP7]

Originally Posted by 71CHEVYSHORTBED402

Just some history. She blew a cork the day I was fired because the boss was a Dk. Abusive guy, they didn't need a reason and didn't, short I saw him in his office getting a lap dance. Geez, lost my Sheba two days later. On the bright side, it allowed time to tend her, and the place hired me back a month later for more $.

..................

What ???? I have no clue what you said...?

Is that some new kind of Zgen language?

.

[weq92f]

.

FWIW, I switched from conventional to full synthetic last winter. Have changed the oil once since then...have noticed no new leaks or anything strange at all. This on a mostly stock 402 cast block and heads w/roller cam.

Now I'm wondering what the bottom of my pan looks like. Maybe next oil change I'll snake a camera in there and have a look see.

-Kevin

[Stocker]

Originally Posted by GSP7

What ???? I have no clue what you said...?

Is that some new kind of Zgen language?

.

Glad I am not the only one left wondering....

[Willshook]

Originally Posted by 71CHEVYSHORTBED402

There are mixed opinions ZDDP or any additive are necessary, and in some cases can reduce performance.

I'll take one pass, and haul ass These discussions always get heated with links to YouTube videos, forum posts, my brother said, etc. I don't do social media conflict, but given the importance of this topic I'll make a brief exception Anyone with genuine questions is welcome to PM me.

Every single flat-tappet cam manufacturer notes this requirement. Period. The more aggressive the cam profile is and the higher the spring pressure, the more critical this is. There's no reason not to just run the right oil; costs about the same and is just as easy to get.

Might get away with it with stock 80# springs and an "olde skool" mild cam. Might not. Worth the risk? I don't think so. You decide.

There's no way 1000 - 1300 ZDDP can "reduce performance"; this was the standard until the API SM spec came out. Additives are a Bad Idea and can cause spark plug deposits because they often add 5000+ PPM ZDDP and other garbage.

I couldn't quickly find a data sheet, but Durablend notes that it complies with API SL, which requires at least 1000 PPM ZDDP.

I'll let the thread proceed without me from here

[jumpsoffrock]

I have a 1956 ford with a 223ci inline 6, and the previous engine was on it's way out in 2022--it was rebuilt locally for me in 2010. It already had a couple leaks, and dismal oil pressure, slight rod knock.

I needed truck to run once or twice a week for a few more months and figured I'd try synthetic, since I was taught it should actually help oil pressure due to synthetics ability to withstand head and have more ideal viscosity at operating temp.

I started running plain valvoline/mobile 1 5-30 or 10-30 full synthetic. It bumped up the oil pressure about 5 (very much needed) psi. Oil leaks did not get worse--engine ahd about 60-80k miles on it at the time.


Quite frankly, after many years researching, talking to engine builders and my own experience:
1)can't switch back and forth from/to synthetic: MYTH

2) Synthetic will make your engine leak more: MYTH

I was taught in an engine rebuilding class I took in 2009 at a local community college that low valve spring pressures will not require ZDDP to the same levels as more hi performance related engines, and in theory, wimpy engines like my 120hp 223ci Ford don't actually need extra ZDDP additive.

I figured I would be my own test dummy, instead of talking trash on the internet like everyone else.

The truck was my daily driver for 1.5 years between 2011-2012, another 1.5 years between 2016-2017, again between 2019 and early 2020. with the old flat tapped solid lifter engine. I stopped adding ZDDP in 2013.

The cam in that engine never went flat.

I built a new engine without replacing the cam that was in it in 2022, and after 20k miles between september 2022 and today, it is my only legal tagged insured vehicle, driven 7 days per week, and it hasn't flattened the cam yet. I use 5-30 Royal Purple because you can grab it at walmart. Oil changed every 3000 miles with mobile 1 filter.




There are lots of myths and paranoia scares on the internet, tough to sort out the truth from the paranoia.

[Steeveedee]

I put a synthetic oil in my truck last oil change. Pressure at hot idle in gear is still just under half gauge, so less than 30 psi? No leaks, but it didn't leak before. It also quit using oil. That was a surprise. About 95k miles on the rebuild (done about 40 YA), and it used oil about 1 qt in 1k miles.