Synthetic vs. Regular Oil
 

I have seen various claims about synthetic vs. regular oil. An article in the local newspaper stated a 20% improvement in fuel economy; it is also claimed that synthetic oil's change interval is twice that of regular oil (3000 vs. 6000?).

Do these claims hold water? Is synthetic oil worth the additional cost? Would it be worth my while to use it in my '92 VX? Let's face it. I'm such a miser that I'll try just about anything within reason to boost my fuel economy even further than my present 46-47 mpg (other than ridiculous infomercials :D ).

Usually I have seen claims of 1-5% increase in gas mileage when using synthetic oil. I went from regular to synthetic, and I haven't seen any difference that I can attribute to synthetic oil.

I change mine at approximately the same intervals as I would regular oil...3-5k depending on other life pressures. What I have noticed is that my intervals where I need to ADD oil seem to be getting longer...

JB, how in the world do you get 21 mpg out of a Cadillac Eldorado? Just curious.

I run synthetic in all of my vehicles. When I ran conventional oil I changed it every 3,000 miles. On synthetic I go every 5,000. I can probably go farther, but I find it convenient to get my oil changed when the mileage is divisible by 5,000. It is easy to remember when it needs to be done. For example, I did my last oil change on the Beast at 150,000 miles. I know when I get to 154,500 I will make plans to take it in for an oil change within the next week or 2.

-Jay

Hadn't thought about the change in intervals. I use 3k with regular oil right now, and it's handy to keep track of tire rotations; I rotate tires every other oil change (6000 miles per switch). Going to 5k would throw a monkey wrench into that...6k would work just perfect. Could always get some of those window stickers to keep track.

I always do my oil change and tire rotation at 5,000 miles. Its just easier for me.

-Jay

I did a 20k mile test with 5w-30s. One was M1, the other was Quaker State conventional.

10k miles each, over all conditions each, over all seasons each.

The difference wasn't even a full tenth of an MPG.

I change at 5k mile intervals and don't really like to go further. Modern conventional oils are pretty darn good now. I don't think I'll buy any more synthetics.

Your newspaper writer is on crack. Those claims are ridiculous.

You can check out BITOG, the generally accepted authority on oil, for more information than you ever wanted to know.

I use synthetic in my VW because it's what the manufacturer designed it for, so I wouldn't expect it to do so well on dinosaur juice -- and anyway, VW specifies 10,000 mile oil change interval on synth, no way I'd want to reduce that! :) In my other vehicles I use dinosaur juice at the manufacturer's recommended interval (in my truck, it's when the "Change oil" light comes on, at 5 to 8 thousand miles).

I've never had an engine fail or wear due to insufficient oil habits, and I can often be forgetful, cheap, and careless about it. I don't even KNOW anyone who should have changed their oil more often or used better oil. I suspect that most cars go to the junkyard without any problem attributable to oil habits, even if the owner didn't have good habits.

I've been working with synthetics for about 25 years. From my personal experience and a fleet I managed for 5 years the gains varied from 1.5-8% depending on winter/summer and/or short trip versus highway driving.

Bottom line is yes, synthetics can give some added mileage.

Per extended drains? Absolutely, no question. The length will vary on the type of oil used, the type of driving done and to some extent the vehicle.

Most of my personal equipment gets an oil change once a year which is on average about 10K miles and I also use a synthetic based filter versus the cheaper or OEM filter when possible.

Will synthetics save you money? In my case it does.

One thing too about synthetics is we simply use less oil & fewer filters to clog the landfills where recycling filters isn't available.

It can depend on the mileage and type of driving you do. This should be handled on a case by case basis. To many variables are involved to make a blanket statement.

1. I drive the car mostly on the freeway.
2. I keep between 55 and 60 as much as possible.
2a. Don't tromp on the foot feed.
3. Run 42 psi in the tires.
4. Relax (don't let others get my goat).
5. No A/C. Broken. The wife, however, is after me to fix it, so that will change soon.
6. Coast whenever possible.
7. Draft (at a safe distance, of course...if there is a choice between gas savings and safety, safety should come first) whenever possible.
8. This is an '83 Eldorado...3800 lbs (smaller by far than the old school Eldos), and a 250 cu. in. engine instead of a 500 cu. in. engine. Also overdrive transmission, and lock-up torque converter. The car was designed to get better mileage.
9. Always use the fuel economy readout...keeps you mindful, if nothing else.

According to the readout (the car comes with a sort of stone-age scangauge built-in) on trips to LA and back I have been getting about 25 mpg...mileage drops with a few trips in town to the grocery store...

The car, as it stands, is an aerodynamic nightmare (except for the really sloped windshield)...I've wondered how it would do with some streamlining...