[vidro]

I read through the archives and I read related post. Yet I have no answer that seems black and white to my flippen analytical mind.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Synthetics vs Dinosaur oil. In the literature that I’ve ready it seems that American Petroleum industry had messed around with standard Dinosaur oils so that it is “Environmentally safer”, works better with catalytic converters and EGR stuff. In doing this they decreases the Zinc Phosphate which is basically the slippery stuff to minimize wear.<o></o>
For those us driving stock engines from the 60’ 70’ 80’ without roller lifter/cam, I have read that the lack of Zinc Phosphate can cause addition wear on parts.<o></o>
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I started using synthetics in hopes of minimizing wear on my engine which had at the time 130,000 miles on it. I still change the oil regularly, just because there is over 130,000 miles on it. As far as leaks, it is a 289 4v and it is my understanding that these engines have been known to leak with 40 year and the original factory seals still inplace, as probably 50% of most vintage vehicles do.<o></o>
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I would stay with a high grade synthetic if it wasn’t for one comment I read last week.
The following is an excerpt from this Article I found on the internet written by Tom TorbJornsen , Maintenance Editor, AOL Autos.<o></o>
Disclaimer I have no clue of this guy’s credentials, or who he is. Nor do I know anything about AOL Autos.<o></o>
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The question:<o></o>
Q: Should I use Synthetic oil in my car?<o></o>
A: That depends on the vehicles age and the carmakers recommendation. Older vehicles with high mileages tend to have excessive mechanical wear in the engine, allowing for internal oil leakage. For vehicles with high mileage ,it is not recommended to use full synthetic oil because it is thin and very free flowing, and use of it results in oil consumption” <o></o>
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First does anyone have an example of what “internal oil leakage”? Would this be like valve seats leaking or oil blowing past the rings?<o></o>
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The next question is, if a vehicle started with regular oil than went to synthetic, can it go back to a regular oil or a high mileage oil without any major issues?<o></o>

 

[Bad69cat]

DO ___NOT use synthetics on flat tappet cam engines - or you will wipe the lobes off the cam in short order! "Dinosaur" oil is what is required as the zinc (or substitute) acts as a cushion between the lifter and the cam. (Modern roller setups don't have to worrry about that) Royce posted a very good artivle from a magazine (Hot Rod?) that really illustrated this a few years ago.....AND VERIFIED (unfortunately) by many recently rebuilt and destroyed engines.

 

[vidro]

I would agree to using the Dinosaur oil except for what I’ve read about the recent (last 5 years) of the API restricting the Zinc Phosphate. It is my understanding that standard Dinosaur oil is now around 400-800ppm of ZnPh. I’ve been running Royal Purple which is somewhere close to the “recommended” 1200PPM of Zinc Phosphate for flat tappet cam engines. I didn’t really think twice about it till I read that recent article about how synthetics are to “free flowing” for the older cars. So based on complied info it seems older cars are danged if they do danged if they don’t when it comes to oils.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o></o>
And now that I’ve been running synthetic for the past couple years can I go back to dinosaur oil?<o></o>
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I’ve also pondered why would oil company’s spend time and money developing “High Mileage” oils if synthetics and standard dinosaur oil ? <o></o>
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I guess I missed Royce’s post, I’ll search archives again

 

[cj750]

Nothing wrong with using synthetic oil in older flat tappet engines, as long as its the right synthetic.

The critical thing is having adequate ZDDP, an additive composed of (roughly equal parts) zinc and phosphorus.

Standards for engine oil are set by the American Petroleum Institute (API) and the International Lubricants Standards Approval Committee (ILSAC). Prior to 1988 API SF specified a minimum of 1500 PPM phosphorus (and equivalent zinc levels). In 1993 API SG reduced the minimum to 1200 PPM, and it was reduced again to 1000 PPM with the SL specification.

From my own research, 1,000 PPM of both zinc and phosphorus is the minimum required for flat tappet camshafts, and the newer SM and SN oils, both dino and synthetic, fall below this level.

Any oil marked API SM/SN, ILSAC GF-4/5 or ILSAC CJ-5 in grades SAE 0W-20, 5W-20, 0W-30, 5W-30 and 10W-30 is limited to 600 minimum and 800 maximum PPM.

Here's a chart listing the Zinc and Phosphorus levels of various Mobil 1 products:

http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

Regarding the original post, synthetic is not more leak prone in older engines because it is thinner, its because it has greater solvency. That property is good in that it inhibits sludge build up, but it can also wash away accumulated deposits, exposing worn or damaged seals. Personally, I've never heard of any problems going from synthetic back to conventional oil, and can't think of a good reason why there would be, as long as the oil contains adequate ZDDP and proper change intervals are followed.

 

[tbm3fan]

The question:
Q: Should I use Synthetic oil in my car?
A: That depends on the vehicles age and the carmakers recommendation. Older vehicles with high mileages tend to have excessive mechanical wear in the engine, allowing for internal oil leakage. For vehicles with high mileage ,it is not recommended to use full synthetic oil because it is thin and very free flowing, and use of it results in oil consumption”

Interesting comment that made me go guffaw. You want oil to be thin and free flowing at low temps so you get quick circulation on start up. Two, if I use a 10W-30 dino, a 10W-30 HDEO and a 10W-30 syn which one would be thinnest. They are all 10W sitting in the pan and then 30W when at operating temperature. The only difference might be in the HDEO which tends to run slightly thicker. I run 10W since my engines sit around for a week or more before running. A 15W- or 20W- sitting in there takes forever to circulate after looking at it's viscosity. The Cougar, with high spring pressure will use either VR1 or Gibbs 10W-30. The other four flat tappets use 10W-30 HDEO Rotella.The four newer use 5W-20 dino.

By the way Delo 5W-40 HDEO has 1000 ppm phosphorous and 1100 ppm zinc. Remember zinc is a sacrificial additive in that it's presence declines over the miles used. With flat tappet cams you have daily drivers, 2000 mile garage queens, true high performance drivers and strip/track cars. Different amounts of zinc needed. Both high performance and strip/track need high zinc but strip/track can use race oils with little if any detergents. The high performance daily driver needs detergents. I did experiment with Rotella T6 5W-40 in the Polara, F100 and Parklane. Partly to see the effect on start up and the effect on cleaning engines that were never mine originally. Worked great and then moved back to 10W-30 HDEO.

 

[Cougrrcj]

Synthetics are almost too slippery for flat-tappet cams - that's the reason they are NOT recommended for that application. The synthetic oil is so slippery that the lifters are not imparted with the rotation they need to survive, causing lifter-to-cam wear!

 

[doctordesoto]

i went from delo 400 to castrol syntec for classic cars-----loaded with zinc and available in 20-50-----even says not for use in cars newer than the early 90's-----delo works great but it looks worn out when its new
doctordesoto

 

[vidro]

Cougrrcj, I'm sorry but you lost me on that "Too Slippery"? I thought one of the issues with common oils and synthetics was the lack of Zinc and Phosphorus which is the additive to eliminate wear by making things slippery. Did I miss interrupt something?<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o></o>

 

[cyclonelou]

If an engine's seals are old and prone to leakage, any oil is going to be leaking out.
I've used synthetic oil with a zinc additive in an engine with a flat tappet cam and I haven't lost any lobes. And I doubt that I ever will.
I've gone from regular oil to synthetics and back again and I've never had any problems due to that. This on a Ford Ranger I bought new and I have 302,000 miles on it with no leaks. The motor's never been apart and doesn't use a drop of oil or run hot.
If you're a quart low, 100 miles from the next stop, and all you can find is a major brand of oil that's not your type, what are you going to do?

 

[tbm3fan]

By the way the reason the oil is "slippery" is because the molecules are more uniform than in dino. So there is less resistance to flow but that is a good thing as there is less drag.

Also, in this talk about oil what is your oil change interval (OCI)? That goes a long way in deciding which oil you would be best with.