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I was sure this was discussed but tried a search but only found for newer mustangs.
With the way current oil is without ZDDP,, should or shouldn't a person use synthetic oil?
I have 71 Mach 1 with a 351 W 4V . Don't know anything about the engine. Purchased it with the 351 W. It came from the factory with a 302 2V.
I have heard it can lubricate better including seals but may get leaks.
 

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Valvoline makes an specific oil with high ZDDP. VR1. They have a street legal version and non street legal.

Also, 15W40 diesel oils have higher levels of zddp. Shell Rotella T4 is easy to find.
 

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Do a search here on the forum, there are LOTS of current threads on this.

The short answer is that synthetic is just fine, just make sure you have higher levels of ZDDP for a flat tappet cam - if you have one.
 

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I don't think there are any valid reasons for avoiding synthetic oils. Almost every refiner makes a high quality synthetic oil, so there are many fine choices.

The Mobil 1 15w-50 and 0w-40 are the two products I've been using since around 1999 and many tens of thousands of miles. No oiling issues, ever. Pick an oil with over 1000 ppm of zinc / phosphorus and you won't have any problems regardless of brand.

Z

PS. In the rare event you do get a oil leak after changing to a synthetic oil, just fix the leak, don't go back to conventional oils.
 

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After I did my research I also ended up with Mobile 1 15W-50. It has the same zinc and phosphorus level as the Valvoline VR1 oil.



Sent from my iPhone using Tapatalk
 

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I don't think there are any valid reasons for avoiding synthetic oils. .
Cost is always valid when it conflicts ego with actual needs. $4 on 5qts might be 20-25%:x

After I did my research I also ended up with Mobile 1 15W-50. It has the same zinc and phosphorus level as the Valvoline VR1 oil.
Sent from my iPhone using Tapatalk
I hope you used valid info in your research, as in most current. The 15W-50 has gone down in ZDDP over the years from red cap to black cap now silver cap. Its still fine though.
VR1 is listed for racing/off-road for a reason. The consequence is it should be changed more frequently.:nerd:

ZDDP doesn't need to be the definitive factors anymore. Molybendum and Boron serve the same purposes.
 

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I hope you used valid info in your research, as in most current. The 15W-50 has gone down in ZDDP over the years from red cap to black cap now silver cap. Its still fine though.
VR1 is listed for racing/off-road for a reason. The consequence is it should be changed more frequently.:nerd:

ZDDP doesn't need to be the definitive factors anymore. Molybendum and Boron serve the same purposes.

Good question, the information is from the Mobil 1 page:
https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf


Page 3: Zinc 1300ppm and Phosphorus 1200ppm. According to the pdf the information is from June 2019. @1ofAMillion+ : Do you have other values you can share?
 

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This comes up a lot and if you can find them, there are threads with way more info than you want. Zray summed it up nicely. Mobil has taken the trouble to meet specifications with a couple of oils that many vintage Mercedes cars and Porsches require. And put it in writing. Unlike most other brands that hem and haw and rather vaguely "claim" to be good for various older cars. It so happens what is good for those older European cars is perfect for our old Ford engines. The specs are out there and previous discussions of this included a chart. Basically all you need to know is that some of the best synthetic motor oil ever for our cars is the 15W-50 and I just picked some up on sale at Wal Mart for $22 for 5 quarts. What may be the "best" is the Porsche spec 0-40 Zray also mentioned. It meets a higher standard, is not on sale like ever, and is really overkill for my 351W's if you ask me. Good stuff though. The weights are key. They don't sell a different version of 15W-50 that I've seen, if you see those numbers on the full synthetic bottle that's it. 10W-30 and 5W-20 are very different blends intended for different engines.

I have a Japanese engined vehicle that I decided to treat to Mobil 1 10W-30 (correct for 1990's Asian stuff) after a long life of (I imagine) the cheapest oil available. It was unhappy and immediately started leaking small rivers of oil. Mostly from the cam plugs, valve covers, and distributor seal. Never leaked a drop before. That one didn't go too well but new gaskets and seals I've bothered to put on seem to have corked it up. (I still haven't finished changing ALL the gaskets. I don't value the vehicle highly enough.) I've yet to see such issues swapping Fords (new and old) over to synthetic but I keep a sharp eye.

Dirty little secret. If a car smokes blue smoke visibly out of the tail pipe, you can change it over to full synthetic Mobil 1 and the blue smoke will almost disappear about the second oil change. It's still burning oil just as bad, but you and everyone can no longer really see it.
 

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A coworker and I were just recently discussing this subject and doing a bit of google research on the matter. Like others have stated, besides cost differential (which is shrinking quite a bit these days) there is nothing but positives switching to a full synthetic. I just switched my Mustang over from the Delo 15w-40 diesel oil to the Mobil 15w-50 synthetic. I am approaching 80k miles on my 351w, and it’s still going strong.

Regarding the leaks after switching over... synthetic oils tend to clean the motor better than conventional oils. So all those years of running oil that deposits goo on everything, including your seals, the synthetic flushes the goo out which can then cause a leak if the goo was acting like a seal on an already compromised seal. I’m crossing my fingers mine doesn’t develop any leaks after the switch 😬
 

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For some reason a few people still insist on running diesel oil in gasoline engines. There was discussion at another board some time back where an actually qualified petroleum engineer chimed in wondering why in the world would people do such a thing. It implied to him that his entire career spent carefully designing additive packages to best suit the needs of particular engines was a complete waste of time. "Completely ignore what it says on the label and do the opposite. Just pour in any old crap some random guys on the internet say is better with absolutely no scientific evidence to support doing so." He was fairly annoyed about it. I found it very amusing.

It's been pointed out before here that diesel engine oil happens to have an additive in it which makes it suitable for use in many motorcycles that use motor oil in their transmissions and have a "wet clutch". This is a valid practice. The reason to do so is that motorcycle specific oil costs more and is less widely available. None of which is relevant at all to old Mustangs.
 

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Ya, been through this before. Remember this? Maybe some tribologists are just smarter than others or some are Henny Pennys. Apparently a secret cohort of rebels have made an earl that satisfies the needs of three engine applications and meet the critical specs, or maybe its a fake label. So don't trust labels then.
:wave:

As for the 15w50 changing formulations, apparently the last change was for the better, compare the two separated by 5 years. The latest ones were all over 1300. There are always batch variations though.


(ooops, the last is the racing formula which is even higher today.)

If you could find historic data many oils of the 60's have similar levels of ZDDP to today's SM/SN oils and cars lasted fine for the most part and many of ours still would. The need for more pressure protection really becomes evident with higher spring pressures, solid lifters and more radical cams.

And for the OP since the he asked yes, synthetics might make a leak more apparent as it removes crude from around a seal. I have seen the "high mileage" formulas help stop it in such cases.
 

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Ya, been through this before. Remember this? Maybe some tribologists are just smarter than others or some are Henny Pennys. Apparently a secret cohort of rebels have made an earl that satisfies the needs of three engine applications and meet the critical specs, or maybe its a fake label. So don't trust labels then.
Lost me. I see diesel specific API certifications that are more related to the sulfur content of the fuel used in diesels of particular year models clear and mentions of the oil being specific to diesel mention use on that label. So what I see is a label indication that T6 is a pretty darn good oil designed for diesel engines and no reason to distrust it. Am I missing something?
 

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Lost me. I see diesel specific API certifications that are more related to the sulfur content of the fuel used in diesels of particular year models clear and mentions of the oil being specific to diesel mention use on that label. So what I see is a label indication that T6 is a pretty darn good oil designed for diesel engines and no reason to distrust it. Am I missing something?
Nope. I always warm up the popcorn for a motor oil debate... many folks using many different products all with satisfactory results. My only comment on the subject is to utilize your common sense.... There are recommended viscosity requirements for factory bearing clearances and operating temperatures... so, if you're running a flat tappet motor with a standard ring package and bearing clearances about 95% of the time a 10W-30 would be the recommended viscosity. If you're running a roller lifter, low-tension ring package with close tolerances then maybe a 5W-30 would be better at lower temperatures. Unless you're running wider bearing clearances and extreme operating temps I see no reason to use a -50 viscosity product... it takes more energy to pump it which puts pressure on the oil pump and pump driveshaft, it drains back to the crankcase more slowly and may not splash as easily onto cylinder walls, piston undersides, etc.

With regard to API Service Classifications when I went to "oil university" it was beat into our heads with a small plastic mallet to NEVER use an oil with a Diesel Classification listed FIRST in a gasoline engine. If the Gasoline Classification was listed first it was A-OK. This was solely regarding the additive package for the type of use for which the oil was formulated.

As far as ZDDP and zinc/phosphorus is concerned... again, the API Service Classification is a good guideline to what oils have an acceptable level (in my opinion) of these additives... anything newer than, and including, SL, does not. These newer oils are formulated to have lower levels of zinc & phosphorus to prevent damage to catalytic converters and and to also function as a "hydraulic fluid" in engines with hydraulically-actuated variable valve timing mechanisms. Oils labeled for use in other than passenger cars such as "racing", "off-road", "air cooled", "motorcycle", "4-cycle", "Motorsports", etc., typically do not have API Classifications and it's up to the buyer to look at the formulation to determine if it's okay for their engine. FWIW, in my opinion, the oil companies have attempted to "skirt" the governmental requirements by labelling some oils as "racing" such as Valvoline VR1 in common viscosities in the same way that light bulb manufacturers skirted the incandescent bulb requirements by producing "long life" and "rough service" specialty bulbs that are exempt.

That said, my choice for any SBF running standard clearances and regardless of whether it's a flat tappet or roller lifter motor is Valvoline VR1 for a conventional oil and Amsoil Z-Rod for a full synthetic.

Now, for those who say that there's no reason to run a high zinc/phosphorus oil in a roller lifter motor because camshaft lobe wear and break-in isn't an issue it's true... because there isn't a lifter face rubbing on a cam lobe there isn't anywhere near the risk of lobe/lifter damage that there is with a flat tappet motor... On the other hand, understanding how ZDDP/zinc/phosphorus functions, from a chemical perspective, and the OTHER internal engine parts that benefit from this bond, such as babbit bearings, piston rings and cylinder walls, valve tips, rocker fulcrums, oil pump gerotors... all these surfaces with metal sliding on metal... why WOULDN'T you want the protection?

The 'chuck will now step off his soapbox.
 

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Many of them are loosing or removing their API certification status' for the same reason Joe Gibbs, Redline, Royal Purple and some Amsoils don't use them. It costs big bucks to be certified and/or they have levels of ZDDP that exceed what certifications allow.

Just post one link to a cited article or product advertisement that says not to use HDEO in a no-smog gasoline engine and I'll wager mine or any ones eternal silence it can be invalidated.
 
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