Car oil

Asked by Sep 20, 2016 at 04:21 PM

Question type: Maintenance & Repair

What type of oil do I use for a 2004
Mazda6?

10 Answers

4,115

10/30 unless you have over 200k miles you may want to switch to 10/40

31,625

5w20, makes no difference how many miles are on it. Some of them have the recommended oil grade listed on the oil fill cap on the engine. This info is also in the owner's manual.

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9,550

I use castrol 20/50 in all my 4 cylinders. 5 weight anything is way to light, The lighter the oil the more friction not the other way around. I put 600,000 miles on 88 sentra and when I opened it up it looked brand new, no scares on the mains no build up, no blacken burned oil, no hardening of oil on any parts and I sold it running great it had no engine work done to it. this craze to use the lightest oil made and new found belief that thinner is better is a falsehood. I have tried it out both ways, the thinner oil cooks to the engine internals, main bearings slip and rip on bare metal and the piston rings/seals let some of it by the seals and this causes the rings/seals to continue to let more and more by and each run get worse. The valve seals when they start to leak they have to be replaced to stop this leaking into the cylinder, I had hardened oil caking to the every part of the inside with thin oil at 200,000 miles with 3000 mile oil changes. I have seen it with my own eyes. Both these were bought new upon first oil change I changed to 20/50 and the other I went by the owners manual 10/30. The 20/50 motor went almost 600,000 miles without engine work and the 10/30 went 200.000 miles then had to have a new valve seals and at 242,000 started smoking so bad I sold it. My 2 cents.

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9,550

The car in this picture by my tag name (blue CRX) has 20/50 Castrol in it and it never needed any work on its engine either. In that picture it has about 170,000 miles on it in 1994 it never smoked and I adjusted the valves at 140,000 miles and the inside upper head was perfectly clean and at about 100,000 miles I punched a hole in the oil pan in a friends driveway and fixed it there too and when I pulled the old pan off I looked at the bottom end and it was very clean too, none of the mains had any marks or burns or scars, the oil pump was clean nothing in the screen, I was very happy. None of the seals ever leaked, there was no oil caking or any build up anywhere.

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31,625

@enginecreator, I guess you must be much more intelligent than the engineers that designed these engines and put forth the specifications. The "5" part of the oil grade before the "w" has little to due with the oil's viscosity at operating temperature. Perhaps the following link would be helpful....https://bobistheoilguy.com/motor-oil-101/

9,550

Bob 20/50 is fine for 4 cylinders. I have had better experience with it.

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9,550

The "w" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures. For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil. The higher number, following the “w” refers to hot weather viscosity, or how fluid your oil is at hot temperatures. The higher the number, the thicker the oil at a specified temperature.

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9,550

Here in the deep south we have very hot summers and barely cool in winter. I would not want 5 anything in my engines.

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31,625

I have actually seen damage caused by running the wrong viscosity oil in extreme conditions (cold). Too heavy and too cold equals slow flow and possible damage in extreme cases. I would NOT run a 50 grade oil in anything unless the manufacturer recommends it. I also think it is very POOR advice to tell someone to run a 20w50 oil just because it has worked for you when the recommended oil is 5w30. Looks like we will have to agree to disagree on this issue.

9,550

The engineers building the engines the last 20+ years have been using plastic gaskets and they fail to easy. The conditions of an internal engine is no place for plastic gaskets. So they are so intelligent they know how to keep an engine from making it 3- 5 years due to gasket failure and you coming back to the dealer for a repair that cost $1000.00 PLUS. Take your car to the dealer for servicing and see if they fill your 35 pound air pressure rated tires to any pound higher than 32 pounds and we all know that a poorly inflated tire wears out way b4 for its suppose too. We were told to not fill a tire more than 32 pounds and every auto that comes in deflate to 32 pounds. Tech school we were trained and dealerships rip all this out of you for there bottom line. We have to adjust our oil viscosity to where we live and if we go by the dealer for this and leave it to someone else then we only have ourselves to blame in the end because we could of all went to tech/voc school and learned it like I did and if then you go to the dealer to get this idea pounded in that we have to "have" work to keep a job and its done this way and use these under rated high priced parts left on the shelf up b4 the new better parts from the factory because they refuse to throw them away even though we have already have a better version designed to last longer and even the auto parts stores already have a the modified version and everything we take off break it so it has to be replaced with new parts and if that is all you got to do today make it last all day its not coming out of your pocket attitude. I could not keep doing it. I am going to do what is best for me and my engines where I live in my temperature range and if you do not care to do the same where you are then I may buy your car for dirt cheap and fix it and sell it for good money do not have hard feelings. Extreme cold does not affect me but heat does and 50 is like 30 to someone in Canada. So if you live above the mason dixon line I would not use a 20/50 oil so we all know that this should be fully researched for your area. I drive between Middle FL & LA & Al & TX & MS and I use 20/50 in my high reeving 4 cylinder engines to keep the engine oil from breaking down in the heat here and baking to inside of our engines I also change my oil every 3000 miles, if it does get cold here down to freezing I use 15/40, In my v6 & v8 engines if newer I use 10/30 and as these age I use either 10/40 or 15/40 I do not use 20/50 in these engines they do not reeve as high and are designed for low rpm ranges and higher torque. Their oil does not break down as fast but I still change at 3000 miles or 5000 miles with full synthetic.

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