rovertnamrod

I have a stock 2001 civic dx with a d17a1 engine. The oil cap says to put 5w-20 oil in it. However, I live in Florida and I deliver pizzas with my car, so I have been putting 10w-30 oil in it for a while now (Castrol conventional, then Pennzoil conventional, then Castrol synthetic blend, and now I just put Castrol edge syntec full synthetic in it) . That's because it is summer time, and I thought a little thicker oil would be better for the florida heat and the job I do. During the winter I plan on using 5w-20 oil.

I start my car about 40 to 70 times a day during a typical day of work. They are warm starts too. I drive in the city, so it is a lot of stop and go. I do quite a bit of idling too, especially if I get caught in a traffic jam going to the beach, where my average speed is 1 mph in 95 to degree weather. In a typical day of work I drive about 65 to 80 miles, sometimes over a 100 miles on a busy day.

1. So, should I be using the manufacturer recommendation of thin 5w-20, or a thicker 5w-30 or 10w-30 oil during the summer in Florida, or does that even make a difference?
2. Since i'm now running full synthetic, is it ok to use a thin oil even in the heat? Should a conventional oil be thicker to compensate for the heat?
3. What do the 10w or 5w stand for and what do the 20, 30, 40, etc... mean in a oil thickness label?

I'm just looking to keep my engine in the best health possible for the longest amount of time possible. I want it to last at least 300,000 miles if possible.

Traum

Coles Note version:
At this day and age, there is absolutely no reason in using 10W30 oil at all. 5W30 offers every bit as much protection as 10W30 and then some. 0W30 is even better because of the extra protection you get in your morning cold starts. In your case, I would go with Mobil 1 0W30 Advanced Fuel Economy formula. It is an awesome, cheap, and readily available oil that is available in 5QT jugs at your local Walmart.

For the long winded explanation, I suggest you give this a thorough read:

http://www.bobistheoilguy.com/motor-oil-101/

In addition to your choice of engine oil, I would also pay extra attention to your cooling system to ensure that everything is in tip top condition. When you are dealing with heat, the car's cooling system is every bit as important as your engine oil.

lowlife9

why wouldn't you listen to the manufacturer that designed and built the engine to run off of 5w20 ??? i wouldn't personally go past 5w30 particularly with a higher mileage engine.

Coopa B18c5

this might help a little

EM2abe

first off, make sure your cooling system is in pristine condition. lol. that sounds harsh.
second:
if the oil cap says 5w20, then use 5w20. 10w30 is only putting a harsh and unnecessary load on your motor, being that 10w30 is far thicker that the weight of 5w20 at STANDING temp as well as NORMAL OPERATING temp(NOpT).
here's a quick explanation.
10W30
The 10 signifies the viscosity(thickness) of the oil at standing temperature at the time that you first start your motor at ambient temp. the 30 signifies the viscosity of the oil when it is at NOpT after your motor is warmed up. NOpT is somewhere between 198-210 degrees give or take some. anything with a higher viscosity will only put an extra load on your motor and could damage internal parts/ruin your gas mileage/lower the power output of your car etc.... during hotter temperatures, you will be fine using 5w20 being that your motor will warm up to NOpT much quicker that it would on a very cold day. 5w20 motor oil will flow through your motor quite easily at startup. though, if you were to use 0w20, the oil will disperse through the motor with less effort than 5w20 being that the viscosity of the 0w20 oil at standing temp is lower than 5w20. in the end, use 5W20 or 0w20. one or the other. nothing heavier.

Rick hybrid

use 5W20 or 0w20

+1

rovertnamrod

My engine has 58,000 miles on it. I have been using 10w 30 for quite a while now. I'd say roughly for 15,000 miles. Have I damaged my engine any by using that oil in the past?

Oh, and I also read that the main reason Honda recommends thin 5w-20 oil is to improve their CAFE numbers. Is that true?

Traum

At normal operating temperature, the viscosity difference between a 20-grade oil and 30-grade oil is small. You will lose a bit of fuel efficiency from the 10W30 oil because it is thicker (and thus resulting in more internal engine friction), but it wouldn't necessarily result in higher engine wear.

The problem really comes with cold starts and all other starts where the engine oil isn't really up to temp. Oil thickens as the temperature drops, and it doesn't flow as well. Because of this natural property, no oil on the market today, regardless of weight, is thin enough to circulate the engine internals on a cold start. As a result, a typical engine sees the most amount of engine wear every morning when it gets its first start after sitting overnight.

Since a 10W-grade oil is thicker than a 5W- and 0W oil, you end up getting more engine wear every morning when you first start the car. It is probably too much of a stretch to say that you have "damaged" your engine by using the 10W30 oil, but it is probably reasonable to say that instead of getting 300k+ miles out of your engine with a 0W20 or 5W20 oil, you will only get significantly less out of it with a 10W30. (How much less? I dunno. But you will get less. Maybe the engine will only last 150k - 200k instead, or maybe it'll throw in the towel sooner.)

But the point is, 10W30 is an outdated oil grade from a bygone era. It has been completely superseded by the newer grades, and it really isn't the best oil for our D17 engines.

rovertnamrod

I just put synthetic 5w-30 Castrol Edge with Syntec in it. Was also considering 0w-30.

EM2abe

why dont you just use 5w20? i dont get it.....5w30 has a higher viscosity. i do deliveries here and there and i put a lot of stress on my car. sure they arent 1mph deliveries. more like 45mph-80mph deliveries... but i also drive in 115 degree weather. with the A/C blasting. hard accelerations. etc.... and i use 0w20. always. my motor doesnt even burn a drop of oil. 3.75 qt's in. 3.75qt's out. the oil cap say 5w20. why would you use anything thicker?

rovertnamrod

I read that the only reason Honda started recommending 5w-20 was to get better CAFE numbers. And I run my car doing deliveries for hours on end everyday. The engine can stay warm for over 12 hours straight some days, constant city driving for 12 hours with no engine cool down periods. As a matter of fact, today I was delivering to the beach almost the whole day. it was a nightmare, traffic jam each time I had to go out there, could've got there faster by walking, usually took 30 to 45 minutes or so to get out there. It was about 95 degrees out, my engine fan kept coming on the whole time, lots of idling, that's gotta be hard on oil, right? I figured 20 weight might break down faster with all that abuse. I talked to a guy at my local advance auto parts- he said Honda recommends 5w 20 for winter temps and the majority of the country where temperatures are usually more moderate, but not Florida where it is ungodly humid and hot in summer. He recommended 30 weight oil because it is simply very hot down here and I use my car so much in that heat.

martpav

IMHO 20 weight is a bit thin, they recommend this for fuel economy reasons, I personally run 5W30 Full Synthetic, Synthetic to be thinner then conventional oil anyways so the 30 weight will not be putting extra strain on the engine and it will protect your engine better then the thin 20 weight

dakota1820

10w30 though not ideal for a colder climate but when somewhere above 40ish degrees it wont hurt anything at all.