I'm currently using 15w40 Castrol Oil & I'm thinking of switching to fully synthetic 5w40(honda).

What are the vast difference except one is synthetic. Thank you.


PS. I live in a tropical weather & the car was from Japan(left-hand drive).

 

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There's no reason for you to be using a 40 weight oil.

 

Why so? THanks.

 

Tolerances... Lets say you want to break a bolt free. There's zero tolerance between those bolts. Using penetrating oil (thin) you may have a chance at breaking it free. Adding heavy oil will never get you inside the tolerances.

• Oil needs to get places and it needs to get there in a specific amount of time. Heavy oil is slow oil.
• Oil needs to get into small places based on the engineers who built the engine. 40wt isn't going to get into those small places.
• Oil also has to get back to the pan. It needs to flow through passages to get there. The time this takes is also important.
• Velocity of oil also keeps things cleaner. Heavy oil is slow oil.

Over simplified... Sorry.

 

Thank you. What oil would you recommend for my honda fit 2000?

 

My .02 cents... I'm not an engineer. I have nothing to do with the manufacturing of engines. Although I do work for one of the largest diesel engine manufacturers in the world. I see the effort that goes into the engineering. I see the debates between different functions, etc..

When an OEM has a recommendation, it's for good reason. Yes they are seeking value and profit but they have also weighed a few important things.

• They don't want to pay warranty.
• They want to maintain a reputation
• Reputation comes from warranty, longevity, forums like this one and a bagillion other marketing calculations.

When the engineers thought about oil considerations / differences.

• That API rating was picked because it best meets all the goals.
• Goals can take into account the engine, the 02 sensors, the catalytic converter, EGR valves, etc....
• You may not use a drop of oil but oil does make it past the rings, just smaller amounts than you can tell.

Things I don't fully understand but you can research

• oil has a film strength
• oil can shear or tear. At this point they don't protect. Certain additives left behind after the shearing will help protect the metal. Racing oils have higher levels of these additives to help protect after the oil breaks down. Racing oils are often not API approved.

Sorry - Still not an answer. I will be running a synthetic with the appropriate API rating and viscosity rating. I'm only at 1,100 miles at this point. Assuming Mobil 1 makes what I will be looking for.

 

This page can explain a lot.. Some is easily understood. and some is over the top for me and will need more time with google to self educate. - Effects of Shearing


Best page I've ever found for not going completely off the chemistry deep end. - Oil Viscosity Explained

 

Thank you so much for the information, Sir..

Off topic.
I used to own a 2008 Civic Si & I love to slap my i-vtec towards redline and I was using mobil1 fully synthetic 5w20 and i recognize that my engine oil decreases for no reason. Apparently, when i switched to redline oil. I saved more gas mileage, more hp and torque as per dyno results and most importantly no decrease of engine oil.

 

I added a second link to my post above. This helps reinforce and more thoroughly explain how oil functions in three critical ways. In your type of use the Redline oil must have been a better fit.

• oil has to get to the surfaces that need protected
• oil has to remain in the location needing protected
• what the oil additives will do once the oils fail, shear, squeeze out, etc..

 

Awesome. Thanks, bud.

 

The differeence is great. besides the much higher viscosity the non synthetic has a lower trear strength, meaning it is moreeasily 'seeted' out in tin films and thus not lubricating. Additionally the 40 weight is harder to pump thru oil galleries and needs more power, hence less mpg. and it degrades more rapidly, thus needs replacing more often, tyipically half as long as full synthetic. The mixed oil is beetter than muixed but not as good as full synthetic, although tear strength is not even close to fiull synthetic and thats really why its used in racing. When the oil between moving parts sheets, it teas and there isn't lubrication between the meshed parts.

 

I'm stumped at something no one noticed my eyes are acting silly. Did the OP state he had a '00 Fit? But stock Honda recommends 5w-30. Then Honda changed to a synthetic blend 0w-20 all in the name of fuel economy while protection stays the same. Honda also backed a list of older model cars Like 1st gen fit, civic, base RSX, all Accords since 03. only civic si, RSX-S, S2000 stayed 5w-20. If u ever wondered why your mpg was blah, that could be one reason.