Adrenolin

Well was out the other night at a local car gathering and the topic of engine oils came up in a croud of about 25 of us. This escalatedinto a fairly heated debate over the type of engine oil that should be used in the older rebuilt blocks. Many of the old timers were down right clear that the only thing to use was the good old fashion rotella diesel oil because it still contains all the oils/minerals/detergents that the engine ran on years ago. Now I've heard this is pretty much the stuff to use for engine break-in and a lot of the younger guys agreed with this however the younger guys then said that after the break-in something a bit lighter or a synthetic oil should be used. The debate was basically centered around the fact that rotella oil is a low revving engine oil.

I've been (by my father and the 'old timers') told that when the engine is put back into the car it should run the thinker diesel oil. Most of the others said it would be better to run a newer 'todays oil' like Castrol GTX in the car.

Suggestions, opinions, comments?

dugan

hmm. I don't know. my dad makes me run straight 50 weight oil in mine.

Daze

oil has evolved over the last 40 years for a reason, it has gotten better. The old timers will use the same argument that "it worked for years" why change. That is an argument for people not willing to try new things. Its kind of like doing the accounting for a small business by hand vrs using a computer, will doing it by hand wok? YES is it the best way to do it? NO Computers make for less chance of errors and make the process much faster. It is no different with new oils. They work better they make the motor last longer and you get better gas milage. The only time changing to a modern oil is bad is if you have put more than 25K miles on the motor with an older oil and you don't clean it out first when you change to the new stuff.

Tony R

my old man is a mechanic and he talked me into putting synthetic in all my cars.

67mustang302

Break it in on Rotella or something with similar additive packages, then switch to synthetic after like several thousand miles. A lot of old timers are very right abotu certain things, but very wrong about others. I've heard crap from some of them ranging from aluminum heads can't be used on street cars to carbureted engines will never be able to keep up with any EFI engine. Some of them swear that EFI I4 > Carb V8 simply because of EFI. Synthetic oil lasts longer, takes more abuse, flows more easily etc. Plus the newer synthetics have completely badass additive packages that you simply will not find in a mineral oi.

Starfury

With the recent addition of emissions requirements (and similarly catalytic converters) to diesel engines, you're going to be seeing all that ZDDP and manganese disappear out of diesel oils as well. I'm not sure exactly when this is going to happen, but I'd start to look elsewhere for a break-in oil before it does.

Valvoline makes a VR-1 Racing oil that's specifically formulated for flat tappet cam motors, having very high amounts of ZDDP, manganese, and other compounds that help reduce wear on a flat tappet cam. It's not as expensive as synthetic, and it comes in lighter weights than 15W40.

As far as switching to synthetic, you really shouldn't do that before 10k miles or so. It takes a while for all of the friction surfaces to completely mate to eachother, and sythetic oils are such good lubricants that they prevent this from happening. Switching to synthetic right off the bat is likely to result in rings that never seat. So run something like the VR-1 10W30 for the first 10k miles or so, then switch over to your favorite synthetic.

kalli

i'm with the same opinion as above. but what I'm worried about is that when i switch to synthetic then the engine will start bleeding and sipping oil through all gaskets because of it being lighter. I don't know what the PO had in it, but i'm with mineral oil at the moment. any opinions from you guys on this ?

jlg2002

Unless anyone can quote (and supply) scientific evidence to support their opinion this thead is IMO. Put up the data souces.

67 evil eleanor

You may want to search "Amsoil" for a low, or no detergent synthetic, designedfor older engines, that won't disolve the varnish that usually seals the engine from the inside, over time. Ithink the synthetics clean so well that once disolved, the leaks start.Their was a long post on here about a year ago. "Adrenolin", theirs no doubt that synthetic is far superior, I would stay away from the blends though.

kalli

thx evil