King_V

Alright, so, with the 2000 Civic LX I have, I got some more information from the previous owner about maintenance.

I've got 127k miles on it, he bought it at 103k. He says that the person he bought it from did the timing belt at around 90-95k miles, so, that's definitely a relief.

Most other maintenance was done, and, he said the oil's only got 500 miles on it.

BUT.... he's an old-school guy, and says he was using 20w-50, which I assume he's done the entire time he's had the car.

So, yeah, like I said, old-school. Now, I know even older motors didn't typically need it that heavy, and definitely modern motors are typically 5w-30, and sometimes even lighter.

But, this Civic has now been running on 20w-50 for a while. I'd like to switch to the 5w-30 the manual recommends, however:

• Are there any possible adverse effects that the motor has suffered from using such a heavy oil
• Would there be any potential problems switching back to 5w-30
• Should I instead do so gradually, say 10w-40 the next time and see how it goes, then 5w-30 if nothing bad happens with 10w-40?

Thoughts? Recommendations?

mk378

Engines have no memory of what kind of oil was used previously. You can and should switch to a lighter oil right away. Watch the oil level closely though. The only real reason to use 20W50 in a daily driver is when the rings are bad so if 5W30 is used, it would burn a lot of oil.

King_V

Alright, thanks - I wondered if the heavier oil might've played a little havoc with the rings or anything, as they were designed for thinner. Glad to know that's not the case.

But, next oil change, I'll try 5w-30. Actually, the next oil change is probably going to be much sooner, rather than later.

White_EG1

I hate it when people act like they know whats better for there car then the manufacturer.

Yeah, throw some 5w-30 in there.

Txdragon

On bone-stock configured vehicles, I go by the manufacturer's recommendations. Why? Because they employed (or contracted) the engineers that designed the engines and made the oil weight decision based upon their fancy engineering degrees..

My uncle, on the other hand, has ran straight SAE50 in all the vehicles he has ever owned and last year they broke the 900,000 mile club on their 92 F150, and all their vehicles with >150k miles have only EVER suffered transmission problems.

civic402lx

I run 10w30 where I'm at. Works just fine.. Mobil 1 full synthetic.

Nave43

From what ive heard running slightly heavier oil in very hot climates can be good for the vehicle (10w 30 in your case). I know here in PA it isnt uncommon for people to run 10w in the summer and 5w in the winter.

P.S. Mobil 1 full synthetic is where its at

TomCat39

This is far from true now a days.

Mobil 1 synthetic is inferior to other brands.

Last year or so, based on lots of research it was reported that the best synthetic on the market was actually Pennzoil Platinum.

Mobil 1 burns off too easily to be effective. Oil consumption tends to rise with it over even conventional.

Also, for my understanding, the weight of the oil for a vehicle is determined by bearing clearances. Older vehicles with lots of wear do better with heavier weight oils.

Knowing me, I would step down to 10w30 (one of the two recommended weights for the car) and watch oil consumption to see how it goes as was previously mentioned by another poster (except they said to jump right down to 5w30). If consumption is still okay then try the 5w30 and see if it's still okay.

The thinner the oil the better fuel economy you will see as the oil pump doesn't have to work so hard.

If your consumption is unacceptable at 10w30, then you know why 20w50 was being used and you might need something like 15w40 to be in the middle ground area and know the motor is pretty worn....

Best of luck.

Nave43

Do you have a link to the study?

I agree i did burn more oil using the plain Mobil 1 full synthetic, though since moving to the high mileage type i haven't burned any noticeable amount of oil.

TomCat39

Are you aware the High Mileage Mobil 1 is actually semi-synthetic not full synthetic so oil consumption dropped due to the conventional oil blend?

I do not know of the study, but the folks that discussed all the various oils (including premium small chain oils like royal purple) know all the API and SN certifications and follow oils religiously. I trust their knowledge as well as it matches up to my personal experience and also follows typical real world happenings.

At one time Mobil 1 was the best of the best... And like most things, they then ride on that success for a very very long time. Also at one time, Pennzoil was considered one of the worst oils.... Things change and I listen to my mates that border on experts with their knowledge and expertise.

Castrol is a good runner up to Pennzoil Platinum from what I understand.

Matt_EH3

Interesting info... Thanks.

One thing though, I was under the impression that the 1st number (before the "W") was for when the engine was cold, but I may be wrong. In that case, I don't think a 5w30 vs. a 10w30 would make much difference on oil consumption.

Unless the car starts burning a ton of oil before running warm? Could make sense...

TomCat39

There is a common confusion with the oil numbering system. One misconception is the W stands for winter.

The number before the W is the actual weight of the oil, so 5 weight vs 10 weight. So of course, the heavier weight is "thicker" when cold or more molasses like.

The number after the W is the viscosity which has to do with high temperature characteristics.

Even at operating temperature the 10 weight oil will be a touch harder to pump as it's thicker than 5 weight oil.

What I've posted is a pretty basic description. It gets way more involved than that, but I do believe what I've expressed is pretty accurate.

Here is a post from 2007 that is packed full of information concerning oil:

https://honda-tech.com/honda-civic-d.../#post28217708

King_V

In a way, yes. As I've read it, 5w30 means that, at "cold" temperatures, the oil will be about as thick straight 5 (actually a bit thicker)* at that particular cold temperature, but at full operating temperature, it's thickness is that of straight 30 oil would at that high temperature.

* 5w20 and 5w30 are thicker than straight 5 at "cold" - with 5w30 being thicker than 5w20... it gets a little messy-confusing.

This was my go-to for information on oil weights, behavior, etc. 10 pages of info, but very useful and fascinating info at that.

Motor Oil 101 - Bob is the Oil Guy - Bob is the Oil Guy


Despite the thick oil, I've gotten 35.9 MPG on my first tankful, about 75-80% highway driving with cruise control. Definitely going to switch to 5w30 this weekend and see how things go. The previous owner has a concrete driveway, and there wasn't a spot of oil anywhere on it.