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Hd 30 and 40 oils

Is there any benefit in using hd 30 or 40 oil instead of the multi-viscosity types for a 98 Corolla?

When I was 21, I used straight 30w and 40w oils in my 1964 Dodge van. I believed I knew more than the Chrysler engineers who designed that engine. I’ve since learned there are many reasons why it’s a bad idea.

The only benefit I can think of is it costs less than the recommended oils. But that’s a penny wise and pound foolish tradeoff.

If I had a car that was on its last legs and I was trying to squeeze another 6 months before junking it, then I’d throw almost anything in the crankcase. If this is your case, just be careful of the thick oil making cold weather starts difficult.

No. There Is A Benefit In Using What The Manufacturer Recommends, Though …
… in regards to engine life, fuel economy, and starting ability. Use what the Owner’s Manual calls for.

Single weight oil has to be changed more often, as the weather changes, to be as much in the ballpark.

No, and it might actually be detrimental. The single weight oil will not flow quickly during cold starts, and more engine wear will result. Stick with the oil recommended by the owner’s manual.

You have to live in a very warm climate to use 30 or 40 weight oil. 30 weight doesn’t flow very well at anything below 60.

IF you do live in a warm enough climate then straight 30 or 40 is probably superior to multiweight oil. Multiweight oil like 5w-30 is actually 5 weight oil that ACTS like 30 weight oil when it gets hot…where as straight 30 weight oil IS PURE OIL and preforms great for higher tempuratures.

In tropical countries, you have a hard time finding multi-weight oil. 30 0r 40 weight oil is universally used. The benefit of 5W-30 oil is in its ability to flow at low temperatures. If your vehicle never sees anything below 60 degrees, multi-grade oil offers no benefit…

In my restored 74 Nova and 59 T-bird I run straight 30W HD detergent oil all year round as I live in tropical Florida and been doing so for years without any problems. You must remember that newer vehicles have tight tolerances so would use extreme caution.

The straight weight olis are exempt from the lowering of the zinc content which is required for older cars with hydraulic or solid lifers to prevent premature cam wear.

If you have roller lifers the newer oils are fine.

Most of these older engines need a minimum of 1100 ppm of zinc where as the newer grade oils either have removed it completely or have a maximum of 800ppm to prevent
catalytic conveter damage.

There have been reports that engine rebuilders have wiped out cam lobes during cam break in with the modern oils, or engines with cams that have an extremely high lift.

It is true that a straight weight oil is “all oil” and does not contain the polymers
that multi grade oils contain. Never use any straight weight oil that states “NON DETERGENT”.

ALways use what your owner manual states. The owners manuals for the Nova and T-bird
( yes I still have them ) state you can use straight 30W oil all year round in warm climates where the temp does not drop below 50 degrees constantly.

Please respond what geographic are you live. Also is your engine leaking or consuming engine oil in huge amounts?

These two answers will give you the best answer.

We lived in a warm, tropical country for 5 years and the most popular oil was 20W50. Also 15W40 was caried by some stations. Very few service stations still carried staight grades (30 and 40); they were mostly for Heavy Duty trucks and industrial engines.

I would NEVER use a single weight oil in a newer car. These engines were designed for modern multi-weight oils, and accelerated engine wear will most likely happen using them. Use the oils recommended in the owner’s manual ONLY. Most of those straight-weight oils DO NOT contain the additives that your engine needs.

Multi-viscosity oils got a bad rap back in the late 1950’s. As I remember, the 1958 Oldsmobile had problems with camshaft failure that was caused by certain brands of 10W-30 oil not able to lubricate well enough for the high camshaft pressures of the engine. Oldsmobile then said that only straight weight oils should be used in this engine. Tom McCahill, the writer for Mechanix Illustrated did not like multi-viscosity oils. In his book “What You Should Know About Cars” he refered to multi-viscosity oils as “sucker juice” and that 10W-30 was a lousy number 10 and a lousy number 30. He didn’t like detergent oils either. He prefered “Soap in his bathtub, but not in his crankcase”. Well, a lot has changed since the late 1950’s and early 1960’s. Oldsmobile and Tom McCahill are both gone. Oil has improved. I would bet that a multi-vsicosity oil is recommended for your Corolla. Even the owner’s manual for my 1965 Rambler recommended 10W-30 oil which I used.

My manual for my lawnmower engine calls for 30 weight heavy detergent in the summer. I suppose that the air cooled engine runs hotter and that the 30 weight stands up better. A lighter weight oil is suggested for winter use, but I don’t mow my yard in the winter when the temperature is below 35 degrees.

Modern motor oils are more concerned about protecting the ENVIRONMENT than your ENGINE… They KNOW the whole package is going to be “recycled” in 10-15 years…No product is made any better than it has to be.