Uncljohn. I am originally from Phoenix. I know how brutal those summers can get! If I live somewhere where the temperature ranges from 70 to 90 degrees all year long, would there be any need for me to use a multi viscous oil?

 

Your air temperature may only range from 70-90 degrees, but the oil in your engine goes for 70 to around 250-300 degrees. You need a multi-viscosity oil, but 10w30 is the best for your environment.

 

Actually?
The fact that the oil goes from 70 to about 250 degrees has nothing to do with anything.
Other than it is more or less true.

It is how well the oil flows when the weather is cold and how well it protects when the engine is hot.

Part of the answer to this is technology changes things.
That meaning I have an oil company produced 60 some odd page oil recommendation manual that tells how to use various lubricants for your car, truck, motorcycle and tractor printed 1n 1923. Oil then was non detergent and was sold using the following weight method.
Light, medium and heavy. about 5 pages of recommendation by manufacturers names referred to not only the name of the vehicle but whether it was SUMMER or WINTER and you used a heavier grade in the summer and a lighter grade in the winter. Also you did not have to worry about a filter. There were none.
Fast forward to 1956 when I learned to drive, weights were no specified with a number such as 10w, 20w and 30w and so forth and the same thing was true. Except now they had begun to market detergent oils which kept contamination in suspension rather than letting it settle out over night and collect in the bottom of the oil pan. It was not uncommon to have to remove the oil pan from older cars and actually clean it out to get rid of the crud that collected in it, recommendation as to weights used was pretty much 20W in the winter and 30W or greater in the summer depending on the extremes in temperatures you lived in. Something like 10W in Alaska and 40 or 50W in Phoenix. And most but not all cars had oil filters.
Except that Detergent oil kept crud in suspension. You got rid of it by changing the Filter. Which was optional on some cars and not available on others and standard on most cars.
Which meant if you had a filter you did not have to take the engine apart to clean it as a function of maintenance.
Then multi-viscosity oils came out. That meant that you could pick something that worked, that is the oil flowed in the morning when you started the car winter or summer and protected the engine when it got hot also winter or summer. But people had the option of choosing the weight and whether it was detergent or non-detergent and whether they had to use a different oil for the winter and another for the summer.
And my Dad bought me my first car and being a typical teenager I knew everything except stuff I needed to know and I blew the damned thing up because the last time the oil had been changed it was winter and a straight 10W oil had been used. Perfectly o.k. for the car and the winter but in the summer it should have been a 30W and by end of summer the bearings burned out.
A 10W30 detergent oil would have been a good choice except habit for many people were to use a non-detergent straight weight and still was.
I did not start using multi-viscosity oil until some where around 1970 or so.
In phoenix it is not always 70 to 90 degrees. Today it is 27 degrees. Today the 20 portion of 20W50 will be in order when I start my car to go to church. In a month or do it will be looking at 100 degrees again, the 50 portion will protect things when the engine gets hot and will flow in the morning.
My Saturn has a factory recommendation of 5W20. It was chosen when the publicity department for GM determined that you could get minutely better gas mileage and advertise it when the car was built. The engine probably would last long enough before problems were developed to make it through the warranty period of 30,000 miles. Most people traded with in the warranty period so the factory would not have to deal with problems. I on the other hand figured they lied. So I used a 10W30 or up to a 20W50 to protect my engine(s) with. Most Saturns use oil by the gallon some where around 100,000 miles. Mine does not use a drop.
I won! And the factory don't care, they are out of business. And saturns are not the only problem car.

 

I gotta side with UnclJohn on this one. Although my temperatures here in South Mississippi don't get into the extremes he sees, all my Saturns are running on 15W40 oil. I get some strange looks at the auto parts house, but I'm proud to claim that all of my Saturns are not oil-wasters/smokers/users. My '93SW2 is approaching 200,000, the '02L200 is currently at 135,000, and the '09Aura XE is at 88,000. How long will they run? I dunno, but I'll continue to drive 'em till the wheels fall off, and then put more wheels under 'em ...

 

Well guys, I live in Tennessee and my Saturn has 254k miles on it, almost all with 10w30 (first thousand with 5w30 from the factory). It does lose a little oil, but not too much, certainly not by the gallon so I am happy with the 10w30. If you guys are satisfied with what you are using, then I suggest you keep on using it and I will stick with what has worked for me.

BTW, uncljohn, I may have started driving 10 years later than you, and subsequently worked on cars that were 10 years newer than the ones you worked on (oldest was a 39 Ford with a 54 Olds 326 punched out to 350 with an Isky 505 and 6 Stromberg 94's), I do know some of the history on oils. The fact that oil goes from 70 to 250+ is significant because it didn't swing that much back then. More like ambient to 190, less in winter. Those older engines usually had larger cooling systems (16 qt vs, 4 qt today), lower temp thermostats (if they even had one of those) and larger oil pans.

 

You're right as to engine temperatures. Cars from the 30's did not even have thermostats. No need, they did not even have heaters in many cases. You could buy an aftermarket "ARVIN" hot water heater, mount and plumb it your self and put vents in where ever you felt they were needed. Heaters were optional clear up through at least 1960 or so. Thermostats were only installed because engine heat was required to create cabin heat if you had the optional automotive heater.. Thermostats were available in round tubes so you could cut a radiator hose in two and splice it back together with one. Using a piece of cardboard in front of the radiator to get the engine up to some kind of temperature in the winter was not uncommon. The value of the degrees of a thermostat is not what the operating temperature was meant to be kept at, but the minimum temperature the water would get to. The maximum temperature was self regulated by the efficiency of the cooling system and the outside temperature of the weather.
170 degree thermostats were not uncommon. My street go fast cars all run 145 degree thermostats.
Fuel injection though requires a minimum operating temperature by design otherwise the fuel injection will stay in the "cold rich" range an euphemism for "Choke" which the automatic operation of was still optional in the 70's. Todays fuel injection will require a 190 to 205 degree thermostat and a 16# radiator cap to keep the water from boiling well over the operating temperature of boiling at 212 degrees.
My 1930 Ford, my second car after I blew up my DeSoto not only did not have pressurized cooling, a thermostat, a fuel pump, shock absorbers (although they were optional), only 1 tail light, no turn signals but it did have an electric start and the standard crank was issued, the water pump leaked like a sieve requiring the owner to drain the radiator at night and fill it with hot water in the morning both to pre-warm the engine to get the oil to flow so it would not self destruct when it started but to keep it from freezing up and cracking the block. Bars Leak was more commonly used back in the day.

 

Wow uncljohn, you are a history lesson. I had a friend who had a 32 Ford Model A but I never saw it running. It was his "project car" but all it did was sit in the garage. I do remember the shock absorbers that were lever actuated and used two pieces of leather as friction plates. I also knew a guy who had a Desoto (I think) that had a leather disk clutch that was in an oil bath. It was impossible to stall.

I believe that all new cars had heaters as standard by the time I was old enough to be interested in them, but there were those commercials by Cal Worthington and his "dog" spot (the "dog" was usually a different circus animal for each commercial) that offered Dodge Darts with a deleted heater for some ridiculously low price, like $1295 or something. I don't think anyone actually got a car from him at that price though.

 

I worked with a fellow who bought his first car (used for service work and required that he have one) from Cal Worthington. A 1950 Dodge for $500.00, paying so much down and so much a month plus and this is the gotcha! When needing repairs you took it back to friendly Cal and he added the costs to your financing. Seven years later he totaled the car and called up to find out what the pay off was having paid on his $500.00 car for seven years. And good 'Ole friendly Cal settled with him for 50 Cents on the dollar. $250.00.
Cal and his dog spot were millionaires several times over and stories of his actual deals were legendary!

 

I had a similar problem with my 2002. It threw 4 codes though. One code was for the EGR valve, and another was for a camshaft position sensor. My car started to misfire when these codes were thrown. We cleaned the EGR valve out TWICE and the codes were still being thrown. When I went to O'Reilly's they told me that the EGR can cause all sorts of problems if not working properly. I would suggest that you clean the EGR very good by taking it off and spraying it with compressed air. A technician at the dealership I work at also revved my engine while the EGR was off and a ton of carbon came flying out so I would do that too before putting it back on. If the codes still show up I would say buy a whole new EGR valve. It cost me roughly 155 bucks after tax to get a new one from O'Reilly's. Good luck!

 

Got the EGR cleaned and already put back on. I thought it was dirty, but I've never cleaned one before so I have nothing to compare it to. I cleared the codes and it seems to be running well.

On a side note, is your idle air control valve a serviceable item or do you need to buy a new one when it gets dirty?