Conflicting Requirements Re:Engine Oil Viscosity

OldGuy

I'm preparing for my 1st Z oil change at 1200 miles. I'm going to use regular oil for her oil changes until 10,000 mi. The Nissan Owner's Manual prescribes 5 W30. At the same time, I'm preparing to take my Miata out of winter storage and change its oil. Its owner's manual says if outside temps are mostly over 40 degrees F and essentially summer-like, 10 W 30 should be used, 5W30 for climates offering 40 defree F and colder temperatures. My Z will enjoy temperatures over 40 degrees during this oil use period, as summer is one the way. 80 and 90 degrees will happen. I plan to obey the Nissan Owner's Manual and use 5/30 but the Mazda book does provide sensible guidance in distinguishing between warmer and cooler climates when selecting viscosity. Could someone with more mechanical knowledge than I (which would be just about anyone) please clarify this for me.

NISSNISS370Z

i think i will do the same. i went into the dealership to find out what ester was, if it was an additive or some kind of process at the oil company. they told me it's thinner than regular synthetic. this might have been mentioned before but theres pages apon pages over the proper oil to use.

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PapoZalsa

You are right, Conflicting Requirements! Different people and stealership service manager will tell you different stories. I'm taking to dealer that I purchased the car which they told me is was going to be service with "Ester Oil" following Nissan guidance.

The local dealer told me that if I take it to them they will use Valvoline 5W30.

However this has already been discussed, but definitely 5W30 oil.

As far as the Mazda in warmer the weather you want 40/50 depending on the mileage, cold 20/30, again follow the owner's manual. My old lady's 07 RAV calls for 5W20.

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OldGuy

Below is some follow-up writing I've found on the subject. Now, I'm more confused than ever:
Is there a disadvantage to using an oil that flows better when cold, i.e. 5W30 versus 10W30?
Sometimes, but usually not. The crux of the issue is this: the bigger the difference between the cold oil viscosity and the hot oil viscosity, the more the volume of viscosity modifiers and the less the volume of base stock. If you are good about following the manufacturer's recommended oil change interval then stick with the 5W30 if that is the preferred oil for your vehicle, even if 10W30 is acceptable in warmer climates. Older cars may specify 10W30 only. This is because they need a little more viscosity when cold to keep a protective film on the cylinder walls. There have been instances where the larger amount of viscosity modifiers that are present in 5W30 have broken down due to excessive heat and have left carbon deposits on the valves, but this is extremely rare. The proper fix would be to reduce the excessive heat, but the workaround was to use an oil with less viscosity modifiers.

Why do many oil change places, even dealerships, use 10W30 instead of 5W30, even when 5W30 is preferred?
According to Car Talk. Car tips, advice, and troubleshooting. (see link in the references section), as well as many mechanics who have posted on usenet, 10W30 is the closest thing to a one size fits all oil. Many older vehicles need 10W30, and most newer vehicles are okay with it in warmer climates. Since many garages don't want to have multiple tanks of bulk oil they choose to carry only 10W30. The advice that Tom & Ray give is correct, 'it would not be a disaster if you used 10W30, but given a choice, go with the manufacturer's recommendation and use the 5W30.'

IDZRVIT

For normal use, always go with the mfg's recommendation and not what you read on the internet.

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ZKindaGuy

This subject is what I don't get about people here.....if the OEM Owners Manual recommends a partricular type then just go with that recommendation and you are covered if something goes wrong as a result of the oil used...which would in all probability NOT likely happen.

No..instead some people here insist on entering analysis-paralysis and create issues where they don't exist and beat a dead horse into a puree.

OldGuy

...and some people out to be a bit less opinionated and rude. Posting like that is out of line, fellah. Good thing you're responding to me on the Internet and not talking to me face to face.

steveg78

Jeeze. I have to kind of agree about what ZkindaGuy is saying here though. I've read my manual front to back and referenced the service manual as well. Yet I am constantly questioning myself because I read about people changing oil at 500, 1000 etc... I thought maybe I missed something that says the first oil change should be sooner than the recommended 3750. I get the theory but that AND the "which oil" threads just leave me dumbfounded. I've always stuck right to whatever the manual says and that's what I'm going to do here. I don't think posting like that is out of line... I'm sure a lot of folks are confused because of all the different conflicting requirements of which oil weight to use and how often to change...He's absolutely right about creating issues that don't exist here. And I know you simply asked for more elaboration like your Mazda manual clearly wrote out but I agree, just follow the book then you'll never have to question yourself if your motor blows on a 100degree day.

The theory is use a slightly heavier oil if you are in an environment where the temps are extremely high. Use a lighter oil for colder environments like the arctic circle. I would think living in PA, you'll be fine with following the recommended 5w30 year-round.

ZKindaGuy

There is nothing out of line regarding my post, FELLA. There seems to be an obsessive compulsive almost anal behavior particularly in this forum regarding topics that have been clearly laid out in the Owners Manual or discussed ad-naseum over the past year. Many folks here need to quit asking for everyone's opinion on such mundane topics, think for themselves and start to put creedance in the Owners Manual that came with your specific car. It really is that simple....

Modshack

...X2

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