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post #1 of 16 (permalink) Old 08-12-2019, 01:27 PM Thread Starter
 
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Synthetic versus Conventional

Howdy. I have a 1967 Tempest Convertible with stock motor. Any suggestions on changing it from conventional oil to synthetic?
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post #2 of 16 (permalink) Old 08-15-2019, 09:36 AM
 
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Originally Posted by HeleneH View Post
Howdy. I have a 1967 Tempest Convertible with stock motor. Any suggestions on changing it from conventional oil to synthetic?
Just my opinion, my GTO is 54 yrs old (only 127K) and have used regular oil (10W30) in it since new. My other cars/trucks and machinery I have been using Mobil-1 synthetic.

Last edited by the65gto; 08-16-2019 at 04:08 PM.
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post #3 of 16 (permalink) Old 08-22-2019, 08:40 PM
 
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I have a 67 Lemans stock engine and just started using Mobil-1 synthetic 10w30 this year. I liked the reviews on synthetic versus standard oil. I pay About $40. for the oil and filter.
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post #4 of 16 (permalink) Old 08-23-2019, 07:35 PM
 
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Here it is. I have a 2015 Hyundai Accent, 1.6 litre GDI engine with now 100,000 miles on it. Have put 70,000 on it since buying it.

The factory oil weight is the 5W-20 stuff (I believe synthetic is recommended) and the manual says to change every 7,000 miles.

I run 10W-30 conventional oil and change the oil/filter every 3,500-4000 miles. Here in the south the summer temps are 92-100 degrees during the day. I run 80 MPH (2,600 RPM's) on the interstate going to work (about 20 miles of the 32 mile drive) and any time I am on the highway, plus a lot of stop and go. I don't baby the car, but I don't beat on it either. So I use the 30W oil based on the hot summer temps and my driving style. I burn 1 Quart of conventional oil each 4,000 miles - which I think is fairly good.

Decided to try an experiment. Switched to a synthetic oil this past oil change. I have gone 700 miles so far and I am down 1/3 a Quart already. I figure I might get 2,000 miles to a quart - 1/2 the oil mileage I get from conventional oil.

So if my oil mileage is what I think it will turn out to be, or less, then that means if I were to change oil based on the manufacturers recommendations, I would have to add 3 1/2 Quarts to reach 7,000 miles. That's a full oil change as it only holds 3.8 Quarts with the filter.

Hmmm. So if I only use 1 Quart of conventional oil in 4,000 miles and would use up 2 Quarts of synthetic oil in 4,000 miles.......which do you think I would recommend?

Now the argument here may be "but your engine will last longer with synthetic oil." Oh yeah, BS. My 1997 Toyota had 271,000 miles on it before I sold it using conventional 10W-30 oil and burned 1 Quart every 1,800 miles. Still pretty darn good oil mileage use at that high of mileage.

So the oil consumption I am seeing right now would indicate to me that conventional oil is better, and the high consumption of synthetic oil is reason for the manual to state an oil change every 7,000 miles because you are constantly adding fresh oil that extends the overall life of the oil in the engine - less oil changes, but you use more oil.

I guess this is to satisfy the "save the planet people," as the manufacturers push the oil change statistics of new cars versus old cars BUT leave out the fact that you use more oil between changes. And that's how you baffle the ignorant with BS rather than facts.

Using my car as an example, I drive a yearly total of about 21,000 miles each year, and based on 1 Qt of conventional oil burned per 4,000 miles versus 2 Qts of synthetic oil burned in the same 4,000 mile period the BS spin goes like this: What they tell you is that's just 3 synthetic oil changes a year versus 7 conventional oil changes because synthetic oil has an extended life. What they don't tell you is that you will burn 10.5 Quarts of synthetic oil versus 5.25 Quarts of conventional oil in a years time. Can you see the math or am I doing something wrong in my calculations?

I won't be using synthetic oil anymore, nor will I recommend it to anyone. Next oil/filter change will be conventional 10W-30 again.

That's my personal experience, and opinion on synthetic oil. I do not recommend it on any older engine for sure. If you want to use it, it is your choice.
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post #5 of 16 (permalink) Old 08-25-2019, 01:35 PM
 
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Since I'm a new classic GTO owner (it's a 1969), I've been reading a lot of things. Maybe too many....

One of the things I've read in a few places is that modern oils lack sufficient zinc for older engines. One of the sites I looked at was napaonline, which seems to have some good, unbiased articles that don't hawk products. Here's a quote about zinc and older engines:

"Before the 1980s, most engines were outfitted with a camshaft design that used “flat tappets,” which generated more friction than later, roller-cam designs. If left unprotected, this friction can generate damaging levels of heat, and also wear down a cam so much that performance and efficiency are negatively affected.

This wasn’t an issue back in the day, because oil manufacturers employed additives called ZDDP and ZDTP, which used zinc and phosphorus, respectively. Together, these heat-activated additives provided protection for hot spots on a cam where metal-on-metal friction was at its maximum. But they were gradually removed from lubricants as tech changed, which means that modern oils aren’t always as good at providing an effective barrier in certain older motors."


Other articles also point this out and recommend using a zinc additive if you're using modern motor oils on an older engine.

I know there are several experts on this site, so I'd appreciate any observations/comments on the zinc issue before I do my first oil change on the '69 (which by the was has an original, numbers matching 350 HP 400 engine).

Thanks, all.

Tom
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post #6 of 16 (permalink) Old 08-25-2019, 03:06 PM
 
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Originally Posted by Tom McBroom View Post
Since I'm a new classic GTO owner (it's a 1969), I've been reading a lot of things. Maybe too many....

One of the things I've read in a few places is that modern oils lack sufficient zinc for older engines. One of the sites I looked at was napaonline, which seems to have some good, unbiased articles that don't hawk products. Here's a quote about zinc and older engines:

"Before the 1980s, most engines were outfitted with a camshaft design that used “flat tappets,” which generated more friction than later, roller-cam designs. If left unprotected, this friction can generate damaging levels of heat, and also wear down a cam so much that performance and efficiency are negatively affected.

This wasn’t an issue back in the day, because oil manufacturers employed additives called ZDDP and ZDTP, which used zinc and phosphorus, respectively. Together, these heat-activated additives provided protection for hot spots on a cam where metal-on-metal friction was at its maximum. But they were gradually removed from lubricants as tech changed, which means that modern oils aren’t always as good at providing an effective barrier in certain older motors."


Other articles also point this out and recommend using a zinc additive if you're using modern motor oils on an older engine.

I know there are several experts on this site, so I'd appreciate any observations/comments on the zinc issue before I do my first oil change on the '69 (which by the was has an original, numbers matching 350 HP 400 engine).

Thanks, all.

Tom

If you do a Google Custom Search in the upper right hand of this forum, you will find several articles on oil selection.

Oil choices are simply opinion based - based on what we read. I read a complete oil analysis that is on line and the bottom line was not about the ZDDP, but the "shear" strength of the oil - how well it held up under pressure.

If you add too much ZDDP, it is just as bad as not enough - so they say. Brad Penn and the Joe Gibb (Driven Brand) oils are said to be formulated specifically for older cars. Have never used them, so can't recommend either.

It is said that you want an oil having a ZDDP level of 1200 ppm for a flat tappet cam.

So after that, you are on your own in making your decision. You can go nuts just worrying about and researching what oil to use and what is best. Just pick one and go for it
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post #7 of 16 (permalink) Old 08-25-2019, 06:26 PM
 
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Thanks, Jim. I am suffering from a bit of paralysis by analysis. I see that the 65GTO subscribes to your recommendation to just go with a 10W30 conventional oil, so that's the way I'm going to go (of course, using the best 10W30 available).

Tom
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post #8 of 16 (permalink) Old 08-25-2019, 06:50 PM
 
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Originally Posted by Tom McBroom View Post
Thanks, Jim. I am suffering from a bit of paralysis by analysis. I see that the 65GTO subscribes to your recommendation to just go with a 10W30 conventional oil, so that's the way I'm going to go (of course, using the best 10W30 available).

Tom
I use Valvoline Vr1 racing oil 10/30 for flat tappet cams, and add 1/2 bottle of Lucas zinc additive for good measure. I had to order it from Amazon tho. Took a couple of weeks but the price was excellent for 6 quarts. Don't take my word for it tho. Do your own research.
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post #9 of 16 (permalink) Old 08-25-2019, 07:17 PM
 
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Originally Posted by Tom McBroom View Post
Thanks, Jim. I am suffering from a bit of paralysis by analysis. I see that the 65GTO subscribes to your recommendation to just go with a 10W30 conventional oil, so that's the way I'm going to go (of course, using the best 10W30 available).

Tom

Yep, you can over think things, then confuse yourself more and still not reach a conclusion, then sleep on it, let it dwell on you at work, come home, do more research, and still not have a conclusive answer. LOL Then it's a trip to the shrink because you had a melt down.

10W-30 is good for most engines and what factory recommends. You can go with the 15W-40 Rotella which is also a good choice and what many do use and suggest. However, Rotella has a couple different types of 15W-40 and the one you want to get is the "T4", not the "T5" which is a synthetic for newer engines. The T4 is for older trucks, ie ZDDP is in the oil. You can do the research.

So if you just want to be safe, go Brad Penn or Joe Gibb.
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post #10 of 16 (permalink) Old 08-25-2019, 07:20 PM
 
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Lucas also makes a "Hot Rod and Classic Car Oil", which already contains zinc and phosphorus, so looks like the best of both worlds. A bit pricey at $37 on Amazon for a five quart container, but shipping is free.

Here's a question for PontiacJim: in doing research everything says that a zinc additive is only necessary if you have a flat tappet cam. Roller cams are fine with modern conventional oil.

Jim: do you know if a 1969 GTO with a stock 400 ci 350 HP has a flat tappet cam or a roller cam? I believe the answer is flat tappet in doing research, but everything I've found so far is a bit vague, as they mostly talk about the Ram Air engines. Mine is a stock 350 HP.

Tom
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