Old car -- Oil change interval same as new?


#1

I am due to change oil in my old cars, but that got me thinking about how the change interval has been doubled for newer cars.



I am assuming that that is because of upgrades in lubricant science, etc. But, I also assume there has been upgrades in manufacturing technology in these newer cars.



So, the question is, if someone has a 1983 Toyota,should you stick with the old intervals or switch to the longer intervals being used with new vehicles, considering you are staying with DINO oil, btw.


#2

I have done oil changes at 5k for as long as I have been driving. It is a nice and easy number to watch for on the odometer.


#3

Newer or older card, I do the 3K oil/filter change. I am assuming you’re a DIY. Next time you change your oil, take a long hard look at the oil. Does it look so black? That tells you something, right? Changing oil is not only because yuour oil is black, but also oil viscosity breakdowns is at or around the 3K mark.


#4

Op again:

Well, the old cars don’t get driven much. Indeed, none of my cars do, but the newer cars, Camry, Prius (90K and 5K) come out with pretty clean oil, very golden.

The two older ones, Corolla, Tercel (230K and 270K)both have very black oil, despite being driven less than 3K. Change is done at three months, using time rather than miles as a guide


#5

i would change the oil and filter just once a year on the older cars,just make sure you use a good quality oil and you will be fine.here in england most cars have a 1 year or 10,000 miles change interval,some even go for 20,000 miles on synthetic oil!!but like i said before on older vehicles 1 year intervals using a good quality mineral oil is fine.hope this helps!


#6

Oil change intervals have little to do with the quality of the oil today and everything to do with the engine. Older cars that have loosely regulated motors that burn lots of fuel, have big tolerances, and don’t always get up to temp in a quick manner need oil changes more often. Oil change intervals have been stretched so far due to te ability of a computer to precisely regulate air and fuel mixtures as well as the tight tolerances of the motor that contribute to less oil contamination. Change your oil every 3-4 thousand miles on a car built in 1983.

As for oil color-this is not an indication of the condition of the oil. The only way to determine how much life is left in oil is to run an oil analysis, which I encourage people to try if they wish to learn more about their cars.

-Dave G.


#7

I recommend that you stick with the schedule in the owner’s manual.

You are completely right in saying that in addition to changes in the oil there are also changes in the manufacturing that enable longer periods between changes. More consistant dimensioning brought on by statistical process control, better materials, and most importantly technologes that allow the engines to run “cleaner”. These improvements mean that on new cars there is less dilution and less contamination due to blowby.

Remember, the goal is to have the engine last as long as possible, not to have the oil last as long as possible.


#8

Kinda related to this thread - what exactly is it that turns oil from a golden color to black? I know it loses its viscosity over time, but I’m looking for a technical explanation for the color change (not “it gets dirty” :).


#9

You are right. There have been great advances in oil technology and at the same time there have been great improvements in engine design.

It would be wise to use the oil change interval specified in the owner’s manual.

I have see reports that actually showed that new oil did not provide the same wear protection as older oil. The first thousand miles or so were actually showing more wear than at about 10 thousand.


#10

Modern oil is better.

I would extend oil changes on your older vehicle if it has fuel injection and is in good running order. If a carb. I would stick to the old requirements as they seem to have taken that vehicle over 25 years which is well beyond the typical car life.


#11

Which aspect of modern oil do you feel has improved so greatly as to circumvent the contamination issues which are the primary reason we change oil in the first place. If we are being techinical here, modern oil or oil of the past few years has some INFERIOR aspects to oil produced in the late 90’s due to certain government regulations.


#12

There are really a few causes.

The oil becomes contaminated by “particulates”, which are microscopic bits of metal from wear.

The oil also gets contaminated with combustion byproducts from “blowby”, a term that includes the combustion gasses (including carbon) that pass by the rings during the combustion process. This happens in all engines. In addition to the rings’ seals not being perfect, there are gaps in the rings (necessary to allow expansion and contraction) that allow tiny amounts by.

There can also be some “coking”, a process describing basically the cooking of the oil. Remember that it gets really hot in those cylinders.

I’m guessing, but I think the carbon from the combustion process is probably the biggest blackening agent.

www.carbibles.com has a good primer on oils. I suggest a visit.


#13

Thanks mountainbike.


#14

Agree with Mountainbike, for two reasons. First, the 1983 cars with carburetors had very sloppy air/fuel mixture settings, and contaminated the oil a lot more. Secondly, your 25 year old car will now have well worn rings, and the additional blow-by and crankcase oil pollution will require MORE FREQUENT oil changes.

However, offsetting this is the much improved quality of oils, and more additives.

So, on balance, stick to the oringinal schedule and use a standard dino brand of oil. This is your most cost-effective tool for long engine life.


#15

On that old engine, 3,000 to 5,000 miles between oil changes with a new filter EVERY OIL CHANGE will get you. Oil is cheaper than metal. How many miles on your engine? Do you do a lot of short-distance driving? Not allowing the engine to get to operating temperatures will also contribute to the oil getting contaminated quicker. A hot engine gets everything expanded, including and especially the rings, both compression and oil rings. This reduces fuel getting down into the cylinders thus reducing the carbon and other contaminants of combustion and also reduces raw fuel “cleaning” the cylinders and valves thus reducing the oil’s ability to properly lubricate the cylinders. Condensation builds up in an engine with prolonged short trips. This is no good for any internal combustion engine. If this is your case, take it out once a month for an about 30 mile ‘trip’. That ought to get everything up to operating temperatures and dissipate any condensation.