Hey guys, I need some advice on Synthetic oil advice. I am currently running Mobil 1 10w30 in my 91 GT but does anyone know what kind of life I can expect from this oil? My GT only is driven around town and even then, it sees limited hwy miles. I would say that I don't rod the car around town but I'm not exactly light on the throttle. The problem is that I've only put 1,000 miles on the car since I bought it back in May but I had the oil changed back in May, when I started using synthetic. It has been five months now and the oil is still fairly clean. Do you guys think it is safe to go 6 months on this oil if I am putting less than 3000 miles on it within that time frame? It is not that I am too cheap to change it or have it changed but the car simply wont be driven that much because of the city driving.
With synthetic and your limited use, I would send a sample to Blackstone labs at the one year mark. For about $25, you'll know exactly what kind of shape your oil is in. No guessing.
Synthetic can go along way. I read somewhere they tested the limits of Mobile 1 and it started to break down over 9K miles and that was them driving it all the time. If you beat on it or take it to the track and so on, then i would still change it at the 3K mark but since you barely drive it and so on. i would probably do the same, 6 months or 6K miles, whichever comes first.
I've read conventional oil will sometimes say every 3K miles or 3 months, whichever comes first.
When i went to korea last time, i left my 95GT, mobile 1 syn in it. my dad only put 2K miles on it while i was gone for the 15months, when i got back i changed the oil and it still looked golden.
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1995 Mustang GT-Heavily Modded-Sold 2003 Ford Lightning-Sold 1997 Saleen-5.4 conversion-Sold 2005 Mustang GT-Torch Red-Sold 2003 Mustang Cobra-Oxford White 2003 4Runner V8 Sport Edition 4X4
Once a year or every 5000 miles which come first is decent oil and filter change interval if using good synthetic oil like Mobil 1 on Mustang. If you are driving very short distances and cold enviroment then maybe 3000 miles is better.
Sending oil samples to some laboratory is waste of time and money. Engine oil is not that expensive. If you have money to drive a car you have money to change oil and filter once a year.
I would absolutely not drive 25000 miles on 91 5.0 Mustang or any other car without oil change no matter what oil manufacture promises! That kind of oil change interval is only possible when engine manufacture recommends it and you must use specific longlife oil for that.
>> Once a year or every 5000 miles which come first is decent oil and filter change interval if using good synthetic oil like Mobil 1 on Mustang. If you are driving very short distances and cold enviroment then maybe 3000 miles is better <<
That was good advice - 20 years ago. But this is the 21st century, and things have changed. We have cleaner burning engines, better fuel, and better oil.
Look in the factory service manual. Ford recommends a synthetic blend - not a true synthetic. For normal driving they recommend a 7,500 mile change interval.
>> Sending oil samples to some laboratory is waste of time and money. <<
Fleet managers have been doing this for many years. They save bucket loads of money every year by doing this. Why change perfectly good parts if you don't need to? Do you change your tires by a mileage? Or do you look at them to see if they're worn? Oil is the same way. If it's still good, you extend the drain interval. If it's not, you shorten the interval to save the engine. UOA also helps you pick up small problems before they're big problems.
>> I would absolutely not drive 25000 miles on 91 5.0 Mustang or any other car without oil change no matter what oil manufacture promises! <<
That's probably the smartest thing you've said all day. It's been proven over and over again that oil just won't last that long - no matter how good the engine or the oil is.
Oil change intervals are always a topic of discussion. The most common recommendation seems to be every 3K miles. But thats old advice, usually passed down from one generation to another. Or, people are getting that advice from the shop that charges them to change the oil. Current science/engineering just won't support that view.
If you want to be smart, you have to follow the science. This is an engineering issue, not a feel good/emotional/"my grandpa told me" issue.
- My 20 year old good advice was for a travisp11, who is driving a 1991 (17 year old) Ford Mustang of which V8 engine is even more old basis and not for general apply. That time oil change interval was 3000 miles/3months! It is the recommendation on my 1990 Mustang GT's owner guide, I think three months is ridiculous. But even with modern oils I wouldn't extend it over a year or 5000 miles.
Yes of course modern engines are a different story. I change oil and filter on my 1997 Ford Mondeo 2.0 Zetec every 15 000 km (about 9000 miles) which is factory recommendation. I drive it about 20 000 miles/year.
- Doing research of how long can engine oil withstand use is not a average consumers and car users job and not even car servicemens job. There are lots of high paid engineers and chemists doing it for us.
And they are the ones who gives the maintenance and service schedules and recommendations and do the lab things. Our job is to follow these schedules and recommendations if we wan't our cars to function properly and keep their value.
I totally agree with you about this "feel good/emotional/my grandpa told me issue". When it comes to cars there are usually at least as many experts as are car owners.
I like changing mine after 3000, because even after 3000 it is still dirty, and black, which means there are lots of tiny particles getting pumped around in your motor....
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1988 Mustang GT, TTops, 306, AOD with 4r70w gearset and shiftkit, E303 Cam, Ford Racing headers, BBK H-pipe, Flowmaster Cat Back, 3.73's, Traction lok with F150 spring, Eibach lowering kit, B&M Tork Master 2400 Converter, trans cooler, C&L 76mm Mass Air, Accufab 70mm throttle body, K&N filter, Mass Air conversion, Subframe connectors, Lots of Polyurethane, 210HP at 4500rpm, 272 Torque at 3600rpm at the wheels, best 1/4 mile: 14.12
>> Once a year or every 5000 miles which come first is decent oil and filter change interval if using good synthetic oil like Mobil 1 on Mustang. If you are driving very short distances and cold enviroment then maybe 3000 miles is better <<
That was good advice - 20 years ago. But this is the 21st century, and things have changed. We have cleaner burning engines, better fuel, and better oil.
Look in the factory service manual. Ford recommends a synthetic blend - not a true synthetic. For normal driving they recommend a 7,500 mile change interval.
>> Sending oil samples to some laboratory is waste of time and money. <<
Fleet managers have been doing this for many years. They save bucket loads of money every year by doing this. Why change perfectly good parts if you don't need to? Do you change your tires by a mileage? Or do you look at them to see if they're worn? Oil is the same way. If it's still good, you extend the drain interval. If it's not, you shorten the interval to save the engine. UOA also helps you pick up small problems before they're big problems.
>> I would absolutely not drive 25000 miles on 91 5.0 Mustang or any other car without oil change no matter what oil manufacture promises! <<
That's probably the smartest thing you've said all day. It's been proven over and over again that oil just won't last that long - no matter how good the engine or the oil is.
Oil change intervals are always a topic of discussion. The most common recommendation seems to be every 3K miles. But thats old advice, usually passed down from one generation to another. Or, people are getting that advice from the shop that charges them to change the oil. Current science/engineering just won't support that view.
If you want to be smart, you have to follow the science. This is an engineering issue, not a feel good/emotional/"my grandpa told me" issue.
Quote:
That's probably the smartest thing you've said all day. It's been proven over and over again that oil just won't last that long - no matter how good the engine or the oil is.
I was with you 'til that.....
As you said, chemical analysis is the ONLY way to tell...
I know of one Detroit Diesel that went 1,000,000 MILES only adding oil with filter changes. It was torn down and returned to service without so much as regrinding the crank.
Ok so i own a '94 Mustang GT 5.0 and even on the '71 and '79 camaros that are owned in my family we don't change the oil until its 7,000 miles on the car. even with the old engine(not a motor<-- that is electronic) and the oils are still decent comeing out. The reason for this is that we RESPECT our cars, and the oil is good enough to last that long. Mobil 1 Synthetic
Synthetic oil life. 
