Straight weight oils ?

should know.

Is multi-viscosity oil too new-fangled for you? ;)

Why deviate from the manufacturer's recommendations when the manufacturer is the one that designed, built, and warrants the vehicle? Will the people who recommend straight weight oil pay for any engine damage/

I don't know, even if there is any.

I know of a case where from the start - a guy used straight weight 30 detergent oil in his new car, and had no noticeable problems (olds v-8).

For years the use of straight weight oils prevailed.

It makes a guy wonder why he should use multi-weight oil in the first place, if the straight weight oil is suitable for the temp s/he is driving in.

If you are using a 10w30 wt oil, and elect to use a straight weight oil in it's place where the temp doesn't get below the freezing point, then to use a straight 30 wt. oil might be acceptable..

the additive package probably accounts for 20-25% of the volume in a multi-weight oil.

how the detergent added to a single weight oil - stacks up, I'm not sure, and if any additional additive like an anti-foaming agent is used.

for the most part - in an additive package used in a multi-weight oil, most likely the additives' composition is made-up from a petroleum derivative.

good question, wish I had an answer as to why the additive package - is so important, is it cost-effective, or to an extent self-serving, and/or really that beneficial?

mho v=83e

I agree that you avoid some bothersome issues if you stay within the range and type of oil specified by the manufacturer of the automobile. Read your owners manual careful and see what the manufacturer specifies for your car, driving conditions,and temperature.

It just makes everything neater.

If the OP really is a Toyota driver, he will probably be aware of some of the problems that Toyota and other manufacturers have encountered with sludging and destruction of some of their engines. If he has a Toyota that is susceptible to this premature sludging, then he will particularly want to abide by the recommended oil type, and will want to change his oil and filter a short schedules rather than to extend them. Toyota has been pretty good about replacing engines damaged in this way, but it is smarter not to tempt fate.

I'd say stay with mulit-weights, you get better cold-start up lubing.

The only reason I know of to use straight weights is for an older plant that is burning oil, people will use a straight weight because it is cheaper to burn a straight weight.

Other than that, there really is no discernable advantage for a car engine to use a straight weight oil.

Why not use the advice provided by the numerous engineers employed at car manufacturers and oil companies. Just follow the owners manual.

Lower cost. That's it.

--scott

In the early days of multi-grade oils (50 years ago) engines that produced very high oil temperatures would cook the viscosity modifiers in multi-grade oils. Hence, air-cooled engines such as lawnmowers and small tractors and aircraft engine stuck to single-grade oils.

Today, there is no reason any sane person would run a single-grade oil in an automotive engine, or even a small air-cooled engine. Some old aircraft engines have OTHER issues (such as common multi-grade oil additives not being compatible with bearing materials) but for anything the average person has in his garage, multi-grade oil is vastly superior.

What? Any API SM single weight oil is going to have about the same additive levels as any similar multiweight oil. A single weight oil by definition doesn't contain any viscosity index improvers though. Also - many single weight oils are made with hydrocracked base oils, and could conceivably be marketed as 20W-30.

Briggs & Stratton doesn't recommend multiweight (5W-30/10W-30) except for conditions under 40 deg F. They recommend SAE 30 for higher ambient temps.

They do have a recommendation that "synthetic" 5W-30 or 10W-30 may be used year-round, but then again we know how tricky that is.

I tried Mobil Drive Clean Blend 10W-30 in a B&S engine when it was near 70 deg F. On startup it shot oil spray out of the exhaust but settled down eventually. I have a few bottles of Chevron SAE 30 (API SL) that will go in there.

I have been told, but can neither confirm nor deny this, that old VW Beetle engines had an oil-to-air cooler that was used without an oil thermostat, but rather had an orifice that metered the oil to the cooler based on viscosity (so more oil would flow through the cooler when it was thinner, i.e. hot) and that this whole scheme was calibrated for either SAE 30 or SAE 40. It makes sense to me, but like I said, I've never looked deeply into the oil cooler of an old ACVW.

I do use Rotella 15W40 in all my old cars (although I may switch to 5W40 syn. in the R1 after it's broken in.) Seems like a good enough oil.

nate

The advantage is that the viscosity index improvers are less likely to fail... Which is the reason why a lot of air cooled engine manufacturers (eg B&S) don't like you running multigrades (cylinder temperatures being the main problem). Engines which share the same oil with the transmission are also prone to VI breakdown.

The downside is that it doesn't flow as well as a multigrade when cold. You might also care to note the downright crude lubrication system of a B&S compared to typical automobile engine.

10W-30 is a 30 wt oil at normal operating temps however you may need to compromise on SAE20 to get adequate flow at starting, depending on ambient temperatures.

Rarely is there a good reason to depart from the manufacturer's recommendation.

------- I would assume that the use of engine heating apparatus' begin to go into a decline in the north - where you at times would see a cable protruding from the front grill. It was amusing to southerners who witnessed such.

With the availability of "synthetic" oils for consumer use - they were probably pushed further back in the closets.

mho v=83e

20w40 use to be a popular weight used in ford cars, one was called by ford's proprietary name. what was it, is it? why "motorcraft" - for sure.

mho v=83e

------- I would assume that the use of engine heating apparatus' begin to go into a decline in the north - where you at times would see a cable protruding from the front grill. It was amusing to southerners who witnessed such.

*********** We used block heaters on our cars but it wasn't just because oil could get thick. I never had any problems with my cars starting, one of which used synthetic and the other which used dino.

In extremely cold climates, the windows can glaze internally with ice as soon as you get into them, the outsides are already glazed maybe, the door mechanism can fail to work, and they are freaking cold.

The combination of block heater, coupé warmer, and seat warmers make it possible to start up the car and go, safely, in a relatively short time.

doesn't recommend multiweight (5W-30/10W-30)

Tricky? I've been running Mobil-1 10w30 in my 6-horse Briggs & Stratton for about 6 years now. Absolutely no problems, and it goes an entire season without adding any oil. This is in central Texas, where the "season" is mostly 90-plus degree days. The engine is a 1994 model.

I meant tricky as in how tricky it is these days to figure out what's a "synthetic oil" from actual engineering or just marketing fluff.

My experience with the synthetic blend oil was that oil sprayed out of the exhaust on startup in a 4.5 HP B&S Quantum. I don't know if Mobil 1 would be any different, although I do use Mobil 1

5W-30 in my car.

Ah, well SO FAR Mobil has been excellent about using the Mobil-1 moniker ONLY on synthetic oil.

I can't imagine why a synthetic would do that any differently than a dino oil. Smaller Briggs engines are notorious about flooding the crankcase breather when you tip them to one side, and from there the oil goes straight into the carb. I'll bet you just got a slug of oil in there when you tipped the engine to drain the old oil, and the oil that was spraying out the exhaust wasn't the synthetic blend at all but the old oil.

I wasn't thinking so much that it was "synthetic" but that it might have been too thin on startup. I suspect it did probably come from tilting the engine, although that was the oil placed in the engine when I got the mower. The mower (Craftsman) came with a bottle of SAE 30 API SG "lawnmower oil".

BTW - B&S seems to be more specific about their recommendations.

5W-30/10W-30 used to be lumped together. Now they have several categories:

Oil Recommendation

• SAE 30 40 =B0F and higher (5 =B0C and higher) is good for all purpose use above 40=B0F, use below 40=B0F will cause hard starting. * 10W-30 0 to 100 =B0F (-18 to 38 =B0C) is better for varying temperature conditions. This grade of oil improves cold weather starting, but may increase oil consumption at 80=B0F(27=B0C) or higher. * Synthetic 5W-30 -20 to 120 =B0F (-30 to 40 =B0C) provides the best protection at all temperatures as well as improved starting with less oil consumption. * 5W-30 40 =B0F and below (5 =B0C and below) is recommended for winter use, and works best in cold conditions.