Which synthetic oil do you use?

[frankin]

Uh... sorry Dave, but what old boy is thinking is right. You see, the Mazda RX-7 rotary engine actually BURNS OIL. Thats right, they actually have oil injectors that meter a minute quantity of oil into the combustion chamber while the engine is running. So they ALL USED OIL. Mazda recommended against using synthetic oil in these engines due to this characteristic.

And just to clear things up about the old RX-7's (of which I've owned many) Mazda sold them here through the 1995 model year.

...and they kinda did get "banned." The old rotary design couldn't meet the new U.S. Federal emissions laws imposed on the automobile industry for the 1996 model year. So Mazda said "well, these cars aren't selling anymore and we cant meet the new emission control laws, so we'll just not sell them in the U.S. anymore.

The completely new design in the RX-8 was squarely aimed at meeting the tougher emission standards and so now they're availale here again.

And one last note. Synthetics really don't lubricate any better than mineral oil under normal conditions. The only place synthetics are necessary is on a race engine that sees extremely hot oil temperatures... and possibly some cars with superchargers... or ANY car that has a turbocharger!

I have a supercharger and use mobile 1 5/20 synthetic. Change every 3000.
These cars do run warm, and I believe benifit from the synthetic. And I also don't care about the RX-7. I believed it was better not to burn oil. Makes the air smell better too but I do understand why the RX-7's had to.

 

[caseypayne69]

Uh... sorry Dave, but what old boy is thinking is right. You see, the Mazda RX-7 rotary engine actually BURNS OIL. Thats right, they actually have oil injectors that meter a minute quantity of oil into the combustion chamber while the engine is running. So they ALL USED OIL. Mazda recommended against using synthetic oil in these engines due to this characteristic.

And just to clear things up about the old RX-7's (of which I've owned many) Mazda sold them here through the 1995 model year.

...and they kinda did get "banned." The old rotary design couldn't meet the new U.S. Federal emissions laws imposed on the automobile industry for the 1996 model year. So Mazda said "well, these cars aren't selling anymore and we cant meet the new emission control laws, so we'll just not sell them in the U.S. anymore.

The completely new design in the RX-8 was squarely aimed at meeting the tougher emission standards and so now they're availale here again.

And one last note. Synthetics really don't lubricate any better than mineral oil under normal conditions. The only place synthetics are necessary is on a race engine that sees extremely hot oil temperatures... and possibly some cars with superchargers... or ANY car that has a turbocharger!

Thank you Sonicbluw SVTF, these guys can suck my ass. I make a statement and I get slander. Isn't that ban able? :shrug:

Another reason for synthetic oil is like you said it dont burn as fast and stays longer. Hence, longer period between oil changes. Thats all you gain. Like he stated AND I stated. It useless on daily drivers.

I was in the market for a 93 RX-7 thats why I have some background on them. I love those cars.

 

[Danger Dude]

Just to set the record straight. The major difference in conventional or and synthetic oil is with synthetic oil there is little to no thermal breakdown even when temps get to the point of boiling conventional oil. The main reason for changing oil is due to the impurities that migrate past the rings in the combustion process. These include acidic and ash compounds that can etch the bearings and greatly reduce engine life. Conventional oil also breaks down at the molecular level and lose viscousity and reduces oil effectiveness. especially under hard driving conditions in the sunny south the desert west.

 

[caseypayne69]

Conventional oil also breaks down at the molecular level and lose viscousity and reduces oil effectiveness. especially under hard driving conditions in the sunny south the desert west.

I live in western Kentucky so that means nothing for me. Nothing against you Danger Dude, but no one drives there Mustang on the highway, in a hard driving conditions sort of way. I'll stick with my Valoline 5-30w. I understand that some motors generally need it. My question is when does a highly modified Mustang really need synth? Is it after a port and polish and valve job? Anyway back to the topic.

 

[Danger Dude]

I live in western Kentucky so that means nothing for me. Nothing against you Danger Dude, but no one drives there Mustang on the highway, in a hard driving conditions sort of way. I'll stick with my Valoline 5-30w. I understand that some motors generally need it. My question is when does a highly modified Mustang really need synth? Is it after a port and polish and valve job? Anyway back to the topic.

As long as you change oil at the intervals required by the manufacturer there will be no problems as far as oil goes. With Synthetic oil you can go almost twice as long between changes and never lose any viscosity.

Bottom line is synthetic is better but that does not mean conventional is bad. It really boils down to personal preference and cost.

 

[BigDaveDogg]

SonicSVTF, I'm aware of how rotary engines operate. It's been a while since I've read anything about them, but I still have a general background. Not that this matters, because I was speaking on behalf of my 4.6. I once wanted an Rx-7...from Hinson Supercars. For anyone who cares to learn about a rotary engine: http://auto.howstuffworks.com/rotary-engine.htm ...now back to oil.

 

[BigDaveDogg]

An interesting article: http://www.triumphspitfire.com/Oiltest.html

 

[silver02stang]

I find it hard to believe no one is using Amsoil. Seems like a lot of Cobra guys prefer it.

i've been running Amsoil in mine for the past two years. i run it with a kn oil filter and the oil is still good at 5k. i used to change mine every 2500k but now i'm up to 5k between changes. once every spring and fall.

 

[-=SVT=-]

Has anyone heard of synthetic oils like Royal Purple gear max being too thin in differentials causing poor lubrication?

Most likely does cause i know it will lower the oil pressure in a motor. That is why if you have alot of miles on your car u shouldnt use it.

 

[XFIRECHIEF]

WOW, where did u ever get a idea like that? IT DOES NOT LOWER PRESSURE!!
If u have lots of miles & switch to synthetics it may use oil because of the wear on the engine & the false varnish seals the dino oil formed being cleaned off with the synthetic oil. Then because of the wear the oil passes though.

 

[-=SVT=-]

WOW, where did u ever get a idea like that? IT DOES NOT LOWER PRESSURE!!
If u have lots of miles & switch to synthetics it may use oil because of the wear on the engine & the false varnish seals the dino oil formed being cleaned off with the synthetic oil. Then because of the wear the oil passes though.

I was told it did by my buddy i just thought it to be true. He is a ford mechanic. But mabybe i just didnt here him right. What he said made sense. I dont know who to believe!!!!!!!! :shrug: :rollseyes

 

[Danger Dude]

I was told it did by my buddy i just thought it to be true. He is a ford mechanic. But mabybe i just didnt here him right. What he said made sense. I dont know who to believe!!!!!!!! :shrug: :rollseyes

The viscosity of oil of a particular weight is the same whether regular or synthetic. It will not lower pressure. If you read my post further back I mentioned I was part of a study with almost 100 company vehicles and some had well over 150,000 miles and all vehicles had much less metal wear than with conventional oil. We did spectrometric oil analysis of all oil as well as microscopic sampling of filters and no matter what mileage of a car you get improved lubrication benefits with synthetic oil.

I will also say that the average mechanic is not well educated in oil as most never went to College and went to a tech school. Now I am not implying they dont know engines but engineers are the ones who develope engines and oils. I have heard some outlandish crap come from what I thought were knowledgeable mechanics.

Here is what is the reality of information. Paying more for oil or filters does not mean a better product. Advertised claims are just that advertisements which are generally overstated claims. Automechanics are not the end all of knowledge. If you use a good oil whether Synthetic or regular and take care of your car and change oil as specified by the manufacturer you will have a good chance of having a dependable car for a long time.

But the truth is any synthetic is far better in lubrication and preventing wear than conventional oil period.

 

[99BadAsp]

I use Amsoil both oil and filters.

 

[stangsx2]

Mobil One my 89 has 307170 miles and now it needs bearings low oil pressure its 5-6 pounds hot. 76 Capri 240000 miles sold it still ran great and the cobra 70k and no loss in oil pressure. Mobil One holds the org patant for syn oil.

 

[svtcontour]

Everyone will laugh but I've always used Canadian Tire Synthetic oil (I think its made by Imperial oil). Sometimes I use Walmart's Tech2000 synthetic.

My SVT Contour has close to 270,000 Km and knock on wood still not burning a drop of oil. Not sure if thats considered very high mileage or not but at this rate I think I can hit 1/2 million on the motor

 

[wedge 67]

i use amsoil 15-40 in my cummins 4x4, castro synthetic 20-50 in my 67 fastback, mobile 1 10-30 in my LT1 vette, and screamin eagle fully synthetic in my harley softail custom as for the probe.......are you soppose to change those?

 

[neatofrito1618]

I use Mobil 1 oil and a Mobil 1 oil filter.

 

[SnThetcOil]

The drain intervals are recommended by the vehicle manufacturer and this is with using standard drain oils, be they synthetic or petroleum oils. A synthetic oil has the *potential* for extended drain intervals *if* it is specifically formulated to do so. If it is not, then attempting extended drain intervals could cause problems. For best results, follow the recommendations of the oil manufacturer. AMSOIL has recommended drain intervals up to 35,000 miles, Mobil now has a 15,000 mile oil available too.

As for using a synthetic gear lube in the differential, that is what Ford specifies and requires for your car, a GL-5 rated, 75W-140 synthetic gear lube. So whomever told you not to use synthetic gear lube because it is, "too thin", well, they may have some learnin' to do.

A synthetic gear lube in the viscosity 75W-140 is no thicker or thinner than a petroleum gear lube of the same viscosity. In fact, a synthetic lubricant will provide a far superior film of protection than a petroleum lubricant could ever hope to. Film strength is how much pressure it takes to force out a film of oil from between two metal parts and allow metal to metal wear. The film strength of even the best petroleum lubes is only about 500 psi, while the *best* synthetic lubricants, can have a film strength of over 3,000 psi! Not even close. It's like taking candy from a baby.

A top shelf synthetic lubricant will also be very wise to use in your transmission, but only if you want to obtain the benefits of reduced wear, cooler operating temperatures, longer transmission life, improved shifting, better performance/quicker acceleration and improved fuel economy. The choice is yours of course.

Alright, just rolled over to 46,000 this evening so I went out and bought some Mobil 1 5w30 and a Motorcraft FL-820S oil filter. I checked the Haynes manual I picked up a while back, and it stated 97+ 4.6L need 6 quarts, so that's what I put it. All looks good w/ Mobil 1 for now. How many miles do you guys drive w/ Mobil 1 synthetic before changing? I've heard 5,000 miles and 3,000 miles...which is recommended? If it's 5,000 I'll just change it again at 50,000 miles and keep it consistent from there, maybe try Royal Purple. Now I need to look into getting the transmission and rear differential oil changed. I was told not to use synthetic in the differential because it is too thin. If it's 75w90 or whatever, isn't it all the same stuff? And what should I use in the transmission?