Oil

Hatmouse

Hatmouse

Well-Known Member
Joined
Jun 30, 2005
Messages
4,791
Location
Bay area, California
Car(s)
'03 Civic Si
My car's due for an oil change, and is spec'd at 5w-20 (it's the civic K20a3 motor). I've heard some talk about 5w-30 being better, if the motor sees a lot of high rpm use? I was wondering if you guys had any thoughts/recommendations on the matter.

Last oil change was exactly a year ago, I used 5w-20 synthetic blend from conoco-philips (union76) and it's been about 6500 miles since that change.
 
Look at the manual; unless you've modified the engine, listen to the manufacturer's recommendations. Changes in oil weight are usually only relevant for different temperature ranges.
 
Labcoatguy said:
Look at the manual; unless you've modified the engine, listen to the manufacturer's recommendations. Changes in oil weight are usually only relevant for different temperature ranges.
Click to expand...

This.

Check the manual. It should tell you what oil weight to use at what temperature.
 
Yes. And whatever you do, stay far, far away from Castrol. Anything but Castrol!

(Before anyone chimes in - Castrol in Europe is very different from what we have here in the States)
 
Manual calls for 5W-20 at 5000 mile intervals. I was going to give it 5W-20 Mobil 1, and run it for 7500 miles.
 
Mobil 1 is a good choice, but running oil in an engine for 1.5 times its recommended period is asking for trouble.

After doing a course on Tribology, I could go into detail, but here's the simplest answer:

This is your typical life cycle of engine oil with respect to oxidation.

https://pic.armedcats.net/m/mi/mike079/2011/04/03/oxidation.jpg

Oil has additives called anti-oxidants which will extend the flat red line (down the bottom) and try to make the curved section less steep.
This is to increase the life of the oil and not wear out bearings etc.

So by letting the car run an extra 2500 miles, you could be putting the oil in the curved section of the graph, which, over time, may do bad things to the engine. Clog filters, grime buildup, corrode bearings etc.

Sure, it probably won't matter if you miss it by 1000 miles every so often, but if you're missing it by heaps - every time you change the oil, there could be problems in the long term
 
rowd22, your theory just proves that engine oil needs to be changed every few months but it doesn't say anything about mileage. If he manages 7500 miles in just 2 months, I think he will be okay.

FATMOUSE, if you are going to extend the recommended mileage, please use the proper oil filter at least. Don't buy the cheapo Fram and other crap from Walmart for example. Find out what is the OEM suggested filter that the car came with and use that one.

For example my car uses a MANN filter which can't be bought anywhere in local stores, I have to buy it online every time. It's only $3 more than a regular filter but it makes me feel better.
 
rowd22 said:
Mobil 1 is a good choice, but running oil in an engine for 1.5 times its recommended period is asking for trouble.

After doing a course on Tribology, I could go into detail, but here's the simplest answer:

This is your typical life cycle of engine oil with respect to oxidation.

https://pic.armedcats.net/m/mi/mike079/2011/04/03/oxidation.jpg

Oil has additives called anti-oxidants which will extend the flat red line (down the bottom) and try to make the curved section less steep.
This is to increase the life of the oil and not wear out bearings etc.

So by letting the car run an extra 2500 miles, you could be putting the oil in the curved section of the graph, which, over time, may do bad things to the engine. Clog filters, grime buildup, corrode bearings etc.

Sure, it probably won't matter if you miss it by 1000 miles every so often, but if you're missing it by heaps - every time you change the oil, there could be problems in the long term
Click to expand...

I was under the assumption that the 5000 mile figure is with regular oil, and synthetic lets you go further?

Also, when checking the oil, what should I be looking for? I check about every 2 weeks; the level has been constant since the refill, and the color of the oil was golden the most recent check (like on the right in this picture)

engine-oil.jpg



_HighVoltage_ said:
rowd22, your theory just proves that engine oil needs to be changed every few months but it doesn't say anything about mileage. If he manages 7500 miles in just 2 months, I think he will be okay.

FATMOUSE, if you are going to extend the recommended mileage, please use the proper oil filter at least. Don't buy the cheapo Fram and other crap from Walmart for example. Find out what is the OEM suggested filter that the car came with and use that one.

For example my car uses a MANN filter which can't be bought anywhere in local stores, I have to buy it online every time. It's only $3 more than a regular filter but it makes me feel better.
Click to expand...

I'm getting my oil changed on Wednesday, the last change was exactly one year ago. Too long?
 
Yes! Way too long. Some people say you should change every 3 months. Others say you can push it till 6 months. I tend to change mine every 4 months. But once a year is definitely too much.
 
_HighVoltage_ said:
Yes. And whatever you do, stay far, far away from Castrol. Anything but Castrol!

(Before anyone chimes in - Castrol in Europe is very different from what we have here in the States)
Click to expand...
What's wrong with Castrol? I currently use the Castrol 5w-30, and it seems ok. But the oil pressure at start up and initial driving is very high. And I should look into alternative filters too.. hmm..

But, yes, I agree, every 5000miles is the average for a change. Oil is the most important oil in your engine. Always be on the side of caution.
 
Like I said...Castrol in the States is a lot different from the rest of the world. Here it is one of the worst oils you can buy.
 
FATMOUSE said:
I was under the assumption that the 5000 mile figure is with regular oil, and synthetic lets you go further?

Also, when checking the oil, what should I be looking for? I check about every 2 weeks; the level has been constant since the refill, and the color of the oil was golden the most recent check (like on the right in this picture)

engine-oil.jpg


I'm getting my oil changed on Wednesday, the last change was exactly one year ago. Too long?
Click to expand...

Yep, so the picture on the right is normal. The picture on the left is oil subject to oxidation, or the anti-oxidants have past their used-by date. (Among other factors)

The main difference between regular(mineral) and synthetic oil is the pour point. I.e. what temperature will the oil stop moving due to low temperature (<0 degrees C)
Synthetics are useful when the temperature changes vastly from summer to winter for example.

I would suggest every 6 months if you want to be cautious.
 
FATMOUSE said:
And if my oil looks like that, does that mean that it's definitely good, or might it still be bad?

(It looks like that at present)
Click to expand...

Haha, It means there is nothing majorly wrong with your lubrication system. :p

If there was something wrong with the oil or your cars lubrication system, the oil would look different. I'm not a Lubrication Engineer (maybe later in my career??) so I can't tell you from looking at it whether or not your oil is OK.

The point is, your oil seems to be fine and you should change the oil, seeing as you're up to the specified mileage and its been a year since you last did it.



Ps. even if your oil looks black like the picture on the left, the engine can still be used. you'll just increase the wear rate on the bearings
 
Must be different here 6,000 miles for an oil change on petrol cars was the norm, but it is now more like 10-12,000 miles and 1 year for new stuff. But we tend to use synthetics or semi-synthetics.
 
You must log in or register to reply here.
Top