Well, the Cruiser probably should use the 5 W 30 oil but if you insist you can just drain it and fill it up with whatever. (Maybe you should tell the car what you did!!)
The last thing in the world to worry about is mixing different oil viscosities when it’s only the leftover oil that will be mixing with the new oil when changing oil. That stuff equals nothing. Don’t even worry about mixing them half and half.
This has been a very educational thread especially the fact that you can mix oil of different viscosities without any problems. I think I’ll use this 10W-40 for top ups on the PT Cruiser and play it safe and use the recommended grade for the rest.
@BustedKnuckles: It wasn’t the only grade left on sale when I noticed the offer and I 'd heard of 10W-40 so I bought it. After tax, it was $7.50 for 5 quarts and the filter. That was the tempting part.
Wow, what brand of oil was it, out of curiosity? I would use the 10W40 in an older car that calls for it. Using it in the PT can cause lessened gas mileage, extra oil consumption, possibly even ring coking, as someone else mentioned. While you can probably mix oil weights, some brands are not real compatible with each other, I think. I wouldn’t mix 10W40 with 5W30 of an entirely different brand. It’s probably fine, but…
I vote to stay with what the owner’s manual (manufacturer) recommends, unless you are operating the car in something special like north Alaska.
Just a small difference (maybe especially if you understand what those numbers really mean, is not likely to be a problem, but using 20W50 when 10W30 is recommended is generally not a good idea.
DON’T DO IT ! !! Not sure who you are trying to maintain the car for, but would not do it in my car. It’s like putting a regular viscosity oil made for a gas engine in a diesel engine. Use the 10w40 for your lawn tractor or the like. The heavier oil can also cause sludging that may lead to problems down the way.
The heavier oil can also cause sludging that may lead to problems down the way.
Heavier oil doesn’t cause sludging.
I wouldn’t use 10w-40 ALL the time. Especially since the engine calls for 5w-30.
10w-40 is just 10 weight oil with additives in it to act like 40 when it gets hot. 5w-30 is 5 weight oil that acts like 30 weight when hot. To higher the difference in the multi weight oil the more polymers used to achieve the higher oil weight. Polymers are not very good as an lubricant. They are used just to thicken the oil. The less difference the less polymers used…and thus more oil.
Synthetics are different though. Less polymers are needed to achieve the same viscosity.
Generally use what the manufacturer suggests. I see no problem using 10w-40 in mild weather when you change your oil, but do see one for warm up and wear in the colder climates. If you insist on being cheap, at least restrict the use to summer months and splurge on 5w-30 for winter. We used to do this regularly in the old days…didn’t we gang ?
We used to do this regularly in the old days…didn’t we gang ?
Back in the old days we didn’t have multi-weight oil. Used 10 weight for winter…and 30 or 40 weight for summer.
I hear you Mike but my point is that changing oil viscosity is not new nor damaging. 5W has proven it’s worth in winter and on sale 10w-40 on the high end may be better for summer. I see no problem nor do car manuals with charts that illustrate oil viscosity use by temperature…change is good, and I would argue, still the better way to go. With motors that outlast the original owners, it’s not any more necessary then 2500 mile oil changes…but it becomes worth it if it actually saves money too…(by “better” summer use oil being on sale). But then, I feel too it’s cheaper owning separate summer and winter tires and changing them too.
The oil viscosity specifications for your car is 5w-30 in all temps. This is specs from the manufacturer who I would trust long before I trusted someones opinion. There are several reasons why it is best to stick with what is called for. One has already has been discussed having to do with the rings. Another is bearing clearance and that pesky thing called an oil pump. It MIGHT have the cajones to pump heavier fluid through the bearings but I doubt it. When 10w-40 oil was popular there was more bearing clearance than on the modern engines making it easier to pump the oil. But now we have tighter bearing clearances and lighter built pumps making it harder to move heavier oil.
Once multi-viscosity became available I stopped switching from summer to winter. Back then 10w-40 was about all there was available. I used 10w-40 for years. Back in 1990 when I bought my first pathfinder the recommended oil was 5w-30. That’s what I’ve been using ever since in EVERYTHING. My trucks…wife’s cars…lawnmower…snowblower…etc…etc.
As I remember, 10W-30 was the first multi-viscosity oil on the market. I think it came along about 1953. 10W-40 came along sometime in the late 1960s. I first used it in my 1971 Ford Maverick. I thought it would keep down the oil consumption. I was getting about 300 miles per quart. However, the problem was the valve stem seals. After I replaced them, I went about 1200-1500 miles per quart. Even with 10W-40, I was able to start the car when the temperature was -20 F and had sat out all night.
I believed Tom McCahill when he referred to multi-viscosity oil as “sucker juice” in his book published in the early 1960s titled “What You Should Know About Cars”. He claimed that 10W-30 was a lousy number 10 and a lousy number 30, and the only reason for multi-viscosity oil was to save shelf space at filling stations. Filling stations had been stocking everything from 10 weight through 50 weight. I stayed away from multi-viscosity until 1965 when I bought a 1965 Rambler. I decided that since the owner’s manual specified 10W-30, I would stay with it until the end of the warranty period. The warranty was 2 years or 24,000 miles. Since the engine didn’t blow up in the warranty period, I kept on using 10W-30 and had no bad effects.
What Pete said.
Besides, oils today don’t only have to be squeezed between smaller spaces (tighter clearances), they’re also used as hydraulic fluids in variable valve timing systems.
There isn’t actually a big difference between 5W and 10W, but compare the cost of 4 quarts of the correct oil against the cost of replacing the car sooner than you would have had you used the correct fluid and it just plain makes no sense to follow the recommendations of the manufacturer.
One other factor: 10W40 has slightly more viscosity modifiers than 5W30. Viscosity modifiers are microscopic polymer coils that uncoil when the oil heats up, expanding and impairing the oil’s ability to flow. They work great for maintaining resistance to flow (viscosity) when the oil heats up, but they don;t lubricate as well as the base oil.
I vote to use the proper oil. Perhaps you can use your discount oil in the lawnmower.
The small 1 cylinder air cooled engines I have on my mower and tiller call for straight 30 weight heavy detergent oil for most climates. Although this was some years back, I’ve seen two mowers where the rod went through the block and the owner had used multi-viscosity oil in the mower. No more than a quart of 30 weight costs, I don’t think I would take a chance. I have used the same lawnmower for 24 years, followed the manufacturer’s recommendation of 30 weight oil and it still runs well and doesn’t use any oil.
The PT Cruiser won’t know the difference, especially in the summer time…36 posts. Unbelievable…You would think he was going to put 90 weight in it…
Well, FWIW here’s # 37. I earlier mentioned the viscosity charts from the factory manuals for 80s and 90s domestics but this afternoon I ran across the Hyundai factory manuals from 2001 and found the manufacturer had a temperature/viscosity chart that was somewhat in line with the earlier domestics. Hyundai seemed quite definite in limiting 5W-20 to ambient temperatures of 14F or below and even then not for sustained high speed. And 5W-30 was likewise discouraged above 40F or for sustained high speed… The chart indicated that 10W-30and 10W-40 were good from -13* to 105*+, 15W-40 from +14to 105+, and 20W-50 from +14 to 105*+. Why stop this discussion now, Caddyman? It could go on for weeks.
And BTW, 90W is actually approximately a 40W oil. The higher designation is to distinguish gear oil from motor oil.
Don’t use the multi viscosity in lawn equipment. Most owners manuals of lawn equipment will tell you this will likely lead to heavy oil consumption.
Don’t use the multi viscosity in lawn equipment
Depends on the lawn equipment. My lawnmower is a 46" walk-behind with a 14hp Kawasaki engine. It calls for 10w-30. The smaller engines that don’t have a pressurized oil system usually require a straight weight oil.