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Oil

i have three vehicles 06 charger/rt hemi,05 ram/hemi 02 accord 4 cyl. i have always changed my own oil and about three years ago i began using full synthetic oils for all the cars. i have been going about 8k miles between oil and filter changes. all the vehicles use about 2 quarts of oil between changes. is this normal usage and if so should i go back to regular oil and change it more frequently. all vehicles run fine and no smoke is seen from exhaust. no drips either. i am puzzled and with synthetic oil and filter changes as expensive as they are what do you recommend? thanks

First, does the oil you are using meet the specifications listed in the owner’s manual? Are you changing it as recommended in your owner’s manual?

How many miles does you car now have on it?

I’m not sure what you’re puzzled about. If your cars are using oil at about the rate of 1 qt. every 4000 miles I’d be hard pressed to come up with a scenario that indicates there’s a problem anywhere. Oil changes–be it synthetic or conventional–aren’t expensive. Engines are.

What would you save by going back to conventional oil and a slightly more frequent change on your 3 cars? Maybe $100/year? You can’t take your wife out to drinks and dinner for that much. I’d keep doing what you’re doing, it seems to be working quite well.

Hey Nitrodude,

All 3 of your vehicles are of a newer model year. So due to that fact it should be perfectly fine to run synthetic oil through them. With older model vehicles, that tend to have higher mileage on them, Your seals and gaskets at that time are already feeling their age. So when you run synthetic oil through them they tend make even the smallest oil leak a lot worse. The reason for that and the reason why synthetic oils are recommended for new vehicles today is the fact that synthetic oils are manufactured with much smaller molecules. The smaller molecules get into very tight spaces easier than conventional oils and there fore offer much better lubricity, which reduces friction, wear and tear, as well as better heat transfer to the oil. However the smaller molecules also make their way through the smallest crevices, gaps that conventional oil would not be able to seep through. That leads to one problem that alot of people have found with switching to synthetic oil. The synthetic oil molecules are sooo small that they can seep into the rubber of a gasket or seal making them swell, and unnaturaly so to a fault. If you ever happen to switch to a semi-synthetic or conventional oil after switching from a full synthetic the larger molecules can no longer penetrate the rubber in the seals and the seals try to shrink. Well the rubber is of a quality on many vehicles that it wont shrink perfectly back to original dimentions soo it will warp causeing a gap to form for oil to seep through causeing an oil leak. This problem is one that is very common with vehicles around the age of your own and have near if not over 100k miles on them already. Unfortunatly once this damage is done there is almost no way to repair it other than to replace all the faulty seals/gaskets. Even switching back to conventional wont often save you the oil consumtion problem.

So to wrap up is the synthetic oil worth it? Yes it is, but ONLY if you can stick with the synthetic oil EVERY change after that. With your vehicles leaking that much oil in that time frame it is not worth the $, go back to conventional but be aware you will still need to check your oil level consistantly. By the way for those of you I have scared with this info, if you have a much newer model year vehicle such as 2008 ~ +, the rubber quality in seals and gaskets has become much better and no longer suffers the same warping affect that I describe. so you can swap back and forth with no measurable negative affect on the seals.

Hope this helps you out Nitro,
Best wishes!

I have been using Mobil One synthetic oil for 14 years, 220k+ miles in my Olds Alero, 6 cyl. Oil changes are done by me at every 8k to 10k miles with no loss of oil. Also, other of my vehicles & friends vehicles, Toyotas, Chevs, Ranger, Mazda B truck who also use Mobil One and change their oil @ 10k miles experience no loss of oil between changes.

Here we go again but this is just what I do. I use synthetic in the car that requires 0-20 and change at 5000 miles. I use dino in the car that requires 5-30 and change every 3000 miles. These are the mileages that the oil monitor says is about 50%. I would not use syn unless that’s all I could get for the weight oil but I would never go 8000 miles, nor would I want to buy a used car that had oil changed at that interval-just me. None of my cars use oil between oil changes. When someone asks whether or not syn is cheaper etc., it is a red flag that they are more concerned about squeezing a nickel than maintaining their equipment. Again just me, but if you were selling me a car, I would pass.

@Nitrodude: I too use synthetic oil and what I would suggest is that you try a different brand of synthetic oil. I think Mobil-1 is excellent oil, buy my Chrysler vehicles use some oil with Mobil-1 in the crankcase. With Valvoline Synpower they use a little oil, and so far with Amsoil full synthetic, they haven’t used a drop. It seems different brands “agree” better with different engines.

If you can afford it, keep using synthetic. 8 o 10 k is quite reasonable for a limit for this oil.

I Pay $27 For 5qt Mobil-1 Extended Performance. AC Filters Cost 4 Bucks. I Don’t Consider A $31 + Tax Oil Change To Be Expensive, Even Changing Every 5,000 Miles.
Most Conventional Oil Would Maybe Only Save Me About 10 Bucks Per Change.

I too have run Mobil-1 for years and years. None of our cars running on it consume oil between changes ( I always check underhood fluids every week-end).

One of the main reasons I use it is because it gets so blasted cold here that I feel much better asking the cars to spring to life on the south side of 10, 20, or 30 below zero. It flows better at the frigid temperatures and lubricates better. That is fact.

My GM cars call for conventional or synthetic oil of the proper viscosity, but GM warns that below -20*F is considered Extreme Cold and then the Owner’s Manual specifies Ow30 conventional or the same 5w30 synthetic that I already use year-around. Why not just keep it simple and use the full synthetic all year instead of the bother of switching ?

Besides, rightly or wrongly, I figure what’s better at -20*F is also a little better for cold engines on those balmy mornings when it’s zero or a little above, too.

Synthetic handles high temperatures better, also. Using synthetic doesn’t cost, it pays.

CSA

@CSA A 0W30 has to be at least a semi-synthetic. Shell pioneered this grade with their Shell Synarctic, which was a 50% synthetic, and less expensive than full snthetic. I used it for years when working in the North.

@Docnick, Thanks. That’s Interesting. My Owner’s Manuals Just Call It 5w30 Synthetic Oil Or 0w30 Engine Oil. They Don’t Mention That It’s Part Synthetic, Too.

What you’re explaining to me (with what my manual says) goes to reinforce the notion that a full synthetic oil is a better choice for cold weather operation than conventional motor oil.

CSA

JMHO, but I consider a quart per 4k miles slightly excessive even if the car manufacturers do not. The car makers also have a vested interest (countless billions of dollars in warranty reimbursement) at stake when making their claims.
My cars and my family members cars use, maybe, a spoonful of oil between 3500 mile intervals even with 200-300k miles on the clock. Even that spoonful is debateable because the amount is so small as to be near undetectable.

If it’s not leaking, that oil is ending up on the leading edge of the substrate in the catalytic converters where it cakes up; partially clogging the converter and emitting microscopic particles of soot out the tailpipe.

Some people luck out with 8-10k mile oil changes; others do not. It could be that your 8k mile regimen is not good enough based on driving habits, fuel quality, environ conditions, state of tune, and so on.
This can lead to oil coking and seizure of the oil control rings on the pistons; a.k.a. wiper rings.
In turn that leads to oil consumption when the wiper ring is unable to breathe so to speak and does not clean the cylinder wall, or walls, on the piston downstrokes.

Next time the spark plugs are out you should consider running both a dry and wet compression test as that can provide an indication to some extent about ring condition. If the plugs are left in place forever per factory recommendations it should be remembered that aged plugs also factor in to oil condition.

It looks to me that if you are ding your own oil changes, you are at a break even point between conventional and synthetic. Synthetic oil costs about twice as much as conventional, but lasts about twice as long.

BTW, I don’t see anything wrong with your intervals either. I’ve been going about 7500 miles on synthetic and 5500 on conventional and I have plenty of miles on all my vehicles. I’d just recommend that you go back to conventional when the oil consumption goes up to around 2000 miles per quart.

Personally I consider 1 qt every 4,000 miles to be excellent on cars that age.

@CSA The “pour point” of a synthetic is much lower than mineral oil. A good 0W30 has a pour point of -50F or so, providing instant lubrication at start up in cold weather. A 10W30 mineral oil is molasses at that temperature, and the valve gear will be destoyed before the engine warms up.

The Alask Pipeline went to all Mobil1 full synthetic for all their equipment a number of years back. They reduced their lube stock by a factor of 4 since the 0W30 and 0W40 oils were good all year round.

If you made a kitchen comparison, synthetic wouild be a high quality cooking and deep frying oil, and mineral oil more like lard or butter, which congeal at lower temperatures, and burn at very high temperatures.

@Docnick, Thanks. I Feel Even Better Now When I Ask Our Cars To Come Pounding To Life At 20 Below ! I Wondered Why I Could Hear Them Giggling Every Time I Started Them. They’re Very Happy Machines.

CSA

I know we are talking about cars, but if you have a manual start snow blower or generator in the frozen north that must run. Synthetic works great. It can save a rotator cuff. When used in a tractor, it can eliminate the need got a heater…I use synthetics there but never in cars. I like to change my oil at the 5 k mark which I feel is much too soon for synthetic capabilities. If I lived where it’s really cold, I would use nothing but syn.oil.

Interesting that on my new snow blower, it says you can use either conventional or synthetic but the oil change intervals are not to be extended for synthetic. My garage though rarely gets below 40. I don’t disagree with what is said, just don’t like extending the intervals.

@bing
I agree about not extending oil change intervals in these small motors. There has been little over the years to make them as clean burning and efficient burners like a computer controlled FI in a car. The oil dirties up just as much with non filtered particulates…especially without an oil filter. That can’t be good for longevity regardless how good the lube properties of the oil are. It’s cheap insurance as we talk only about a quart or two on something that you do not want to fail or have to replace or repair more then once every twenty years.

" Synthetic works great. It can save a rotator cuff. "

One of my snowblowers has 12v electrics, an onboard battery, and starts with the turn of a key. It shares a common battery with my lawn tractor. I take the battery out of the tractor in the late summer and out of the blower in the spring. It gets continuous use through the year.

Funny thing is that the battery’s life is extended this way. I usually replace the battery before any signs of failing at about 7 years.

CSA