The Stovebolt Site Forums The Shop Area Engine Shop synthetic versus regular oil?

I had my 216 engine rebuilt for a 52 Chevy pickup. I replaced the babbet bearings with inserts, but only replaced the rope type oil seals with new ones. I have about 200 miles on the engine & have replaced the regular oil/filter once. Would it be advisable to change to synthetic oil at some point? Will it lead to oil leaks, which the rope-type seals are known for? Any help would be appreciated. Thanks. Bob

Synthetic will not "cause" seal leaks. That myth got started when high mileage engines were changed over from conventional oil to synthetic. What happens in that case is that there was already a leak present, but was being masked/stopped by varnish buildup in the seal. Synthetic oil tends to very high detergent, which will clean the varnish out of the seals, which made the leaks show up.
You won't have any problems running synthetic, but you may want to wait until you get some more run time on the engine so that is properly broken in.

I am a proponent of synthetic oil and use it in everything I own but the real truth is it is pretty hard to justify in such an old low tech engine. It just isn't made for that application and changing it a little more often and keeping it clean is arguably just as good. But if you like to spend money then by all means go with it. I have used Mobil One exclusivly in all the cars and trucks for many years w/o a single oil related issue but so have lots of guys using auto parts in-house brand oil and saved enough to buy a case of good single malt scotch. So who is right?...obviously it is personal preference.

i would always tell my customers to break in the engine for at least 1000 mile before changing over to synthetic,give the engine a chance to seat in with rings,53moneypit is right,why spend the money for oil that you should change every 3000 miles anyway.i have seen engines with over 300,000 miles on the because the owner change his oil every 3000 mile and thats before synthetic oil were around. you right, its your call!

Thanks for your help folks. Just to baby the engine, I may put in the synthetic/regular oil mix after the engine is broke in. Based on everyone's replies, I have a 2001 Nisson 4 banger with 100,000 miles - no reason to not use synthetic oil in it, right?

I have used both conventional and synthetic oils.

The only benefit to using synthetic that I have ever experienced was the vehicle would start easily the coldest morning that I ever experienced in Mis-Missouri (my thermometer showed about -25 F.).

Power and economy increases may exist, and be measurable in a laboratory, but I experienced no noticeable increases.

Our last shop truck (non-stovebolt) that ran exclusively conventional oil lasted 440,000 miles and the cylinder head was never removed. Got tired of repairing the rust caused from the salt and cinders MoDot places on our highways so that below average drivers can be on the roads in the winter.

Just my experience, others may differ.

Jon.

I have been using syn oil for over 20 years in all of my drivers, but not my tractors yet. That's due to the large supply of mineral oil I have yet to use up.
I prefer a syn oil because of it's increased lubricating qualities and have had good results in using it.
My collector tractors get minimum use, so I doubt that I would realize any benefit from using syn oil in them, but I would use it once my supply of mineral oil is exhausted if the price has not gone out of site.

Dan

I've been using name brand conventional oil in my car for the last 130,000 or so miles. Recently I purchased a semi-synthetic and used it. I'm going to swear to it that my car runs smoother and quieter. I never would've thought it possible on a car with 150,000 but that's my story and I'm sticking to it.

I've been using Valvoline in everything for 30+ years with no issues. When I bought my new Mazda 6 a few years ago, I figured, OK, high tech, time to try synthetic. Was surprised to have the service tech say the manufacturer recommends conventional oil!!!
But, I agree with a previous post, my '40 was not designed for anything but nasty 30 or 40 weight oil. And, since it has not been rebuilt, I'm sticking with it. HOWEVER... if I have it rebuilt, knowing everything is new and tight, I may re-consider synthetic.

Something worth mentioning, though it doesn't really apply to older vehicles, most vehicles built after 2011 do require synthetic oil, some (Cadillac and Corvettes) have required it at least since '99. There are also some cases where synthetic is only choice, as the weight oil required is not available any other way, 0W-20 used in many Toyota and Honda vehicles for example.

the only reason it is specified is gas mileage, it isn't "required" (notice these are the very low gas mileage cars) And how many people here use what is actually specified anyway? I am pretty sure 20-50 isn't specified by any manufacturer.

I had my 216 engine rebuilt by PER in Portland OR and they knew allot about the old engines. I also had insert bearings added. They told me to make sure to add Zinc additive or to buy oil which has zinc in it. They indicated the latest grades of oil have zinc removed. They gave me a bottle of "Enginetech" ZDDP-3.

Hemmings Motor News just announced they have started selling a high zinc supplemrnt oil under their name. I only read the headline but not the accompanying article yet so that is all I know for now.

Gas mileage is only part of it. There are also much tighter tolerances in these modern engine. I don't have the specs handy, but several manufactures have put out bullitens concerning what oil specs should be used. I do know that some of them will even trip a MFI light if the wrong oil is used (Chrysler).

The crank clearances for new engines are very tight,most run with .0008(8tenths).thats why they run 0-20w oil.And cam and lifters are roller on most of them.They dont need thick oil. Can harm the bearings if using heavy oil.

Is there still such a thing as "break-in oil?
GM didn't recommend it for my new crate 350.

the new mustang engines are spec'd at .0003".0005" bearing clearance, gas mileage is the biggest reason they use the thin oil to begin with, the clearances are just a concession to the reality of 0 weight oil. My wifes car spec'd 5W-20, I ran a whole case of 10W-30 through it, didn't seem to hurt it any, it went 190,000 miles running strong. but the transmission died, and there was a very expensive feeling problem with the anti-lock brakes, but the engine was golden.

Yes there is break-in oil, most race part dealers seal some sort of break-in oil. Brad Penn, does a long with Comp Cams. They are doctored up conventional oils.

Joe

I remember back the mid 60 a friend of mine had a brand new Cobra and was racing a Corvette. He beat the Corvette by ten+ car-links and the Corvette driver was complaining how the Cobra's break-in oil had blown back onto his windshield. My friend told him, "I guess you shouldn't have been back there". lol

I was at the Barrett Jackson show in Las Vegas this last weekend. The company that bought out Kendall Oil brand which i forgot their name stated they did not sell a full synthetic oil. He stated that they sold a semi-synthetic because the full synthetic was so slick that it actually made friction on the parts and a rocker arm he showed me had wear on it. My Cadillac 08 DTS requires full synthetic oil. Has anyone heard that before. I am not convinced. I liked their company because it was the only USA company left but not convinced in their study.

They were blowing smoke. Synthetic oils will not do that.
There was a mnetion earlier that 20w50 was not specified by any manufacturer, that is incorrect. Many turbo charged engines, especially Volkswagen and Saabs, specified 20W50.

the volkswagen and saab specs I found indicated nothing more than 10/40, actually 0/30 or 5/30 was the recommended oil for both of them. 20/50, wasn't even on the radar. even heavy diesels don't specify oil that heavy, although the largest diesel engine I have ever worked on was only 7500 HP but they ran 40 weight in those. So I'm not really sure how to compare those apples and oranges....

The cars I mentioned said "20W50" right on the oil cap. with the Volkwagens, it was on both gas and deisel turbo engines. Also, to add to that, I recently serviced an '06 Hyundai Sonatta with a gas engine, it also listed 20w50 as an authorized oil for use in it. Granted, it was for high temp use.

what year were these? I could find absolutely no mention of it anywhere. But whatever the case, 20w50 is really too heavy of an oil for anything in my opinion, 15w40 is excessive in my opinion as well. Except maybe for industrial engines which run continuously.

The Volkswagens and Saabs in question were mainly mid '80s to early '90s models. As mentioned, the Hyundai was an '06. I have a full listing of oil specs at the shop, for pretty much any production car and truck back to the '70s.
15w40 might be exsessive in a gas engine (non turbo), but it is the common grade specified in virtally all light truck deisels.

5w30 synthetic or non-synthetic was recommended (owner's manual/CD) for my wife's VW New Beetle 1.8L 150hp turbo (non-diesel).

Ah that explains it, that is semi old thinking, I have been researching this off and on for a while. Because at work we try to reduce our inventory of lubricants we use and we have it narrowed down pretty good, even Nascar is using 0w30, or 5w30. It seems a lot of things I, and a lot of other people have been taught as gospel, is wrong...in many arenas, such as ac synchronous motors, running at 30 HZ, which I was taught was an impossibility, but is now standard practice with VFD's, there was an article in popular mechanics recently about some fella making a race car that is completely different than anything else, rendering all conventional ideas somewhat flawed. I am just the right age to have seen old school, turn into modern that often directly contradicts the old technology that was touted as fact. I did find an article that was written by a lubrication engineer that was pretty interesting.

here wee i work we use 15w40 fully sync oil in everything new trucks , tractors , blazers, small mowers and rider mowers , you name it ,, its from schaffers , we get it by the drum ,,, i am getting my 235 rebuild totaly wounder if that would be ok for it ???

If you just change your oil every 3000 miles or so you will have no problems with oil breaking down, If you have a early engine you should be using 10/30 or 10/40,or 30 or 40 weight and change it. The clearances are bigger in the earlier engine and you need the thicker oil to "fill" the clearances there,Its always been how you build them.And if you have a later engine put in the thinner oil because of the clearances are tighter 0/20 or what the manufacture tells you to use.People that tell you one oil is better than the next is telling you that because they get a good deal on their oil,All oil is good if you change it regular , Now i know there will be somebody to disagree but for the engines in these old bolters 10/30-10/40 is all you need.Just change it. It feels good to change the oil anyway in these old trucks,You have to work on them anyway.So why not change the oil and see what it looks like coming out.

thats what i am saying if 15w40 is ok i would do it like every 2000 miles

15w40 is prefect! Just change it and drive it!

the 216 has no filter rebuilt bearing clearance to specs syn or regular did put a hour meter on it

I have come late to this discussion but through personal experience, I disagree. My overhauled 1954 235 has 30,000 miles since overhaul and it leaked oil for most of that until last fall when I stopped using synthetic engine oil. Still, have a minor leak but not as much as before. After reading all the post, would a heavyweight oil effect
gas mileage, like 10-50?

I would say yes on the heavy oil and lower fuel mileage. I have seen race cars sheer the oil pump drive from to much oil pressure, and oil filters blown up from the same high pressure. If pressure can damage these items, it should effect fuel mileage just as easy. Can I prove it, NO, but the OEM's didn't change to lighter oil just for the fun of it.

OEM's changed to lighter oil to meet the unrealistic fuel mileage and emission regulations imposed on them, plus the almost nonexistent clearances in modern CNC-manufactured engines are so tight that thicker oils won't fit. What we once considered to be normal oil clearance is "worn out" in today's engines. Running water-thin oil in an engine that measures oil clearances in feet instead of inches is foolish and non-productive.

The major disadvantage to running a very heavy oil is lack of lubrication at startup, especially in very cold weather, as well as increased load on the battery and starter due to the high cranking amperage of turning an engine with oil the consistency of molasses in it. 15W40 flows like a 15 weight when cold, and lubricates like a 40 weight when hot, without compromising seals and other potential leak points in the older engines. Sounds like a win/win situation to me!
Jerry

FINALLY! I've been waiting 5 years for the correct answer.

I love it when these old threads get revived...kinda like when they play an oldie on the radio.

I use 15W40 in all of my Cummins Diesels. But I like Mobil1 15W50 for my older engines.

What is it about the Mobil that you like?