How do I switch from conventional motor oil to full synthetic in a high mileage Civic?

Question

My wife has a 1998 Civic, which is running strong with about 120k miles. I've been thinking that I'd like to switch the motor oil over to a synthetic, but I've heard stories from people that it can be tricky. From what I understand, a simple switch from conventional motor oil to synthetic can cause a loss in power and it could unseat the piston seals.

My question is this: how would I go about switching this car from conventional motor oil to full synthetic?

I have an idea, but I'd like some others' feedback. If I were to start by using one quart synthetic, 3 quarts conventional (the same brand, same weight) for an oil change. The next would be 2 and 2. After that, I'd do 3 quarts synthetic, one quart conventional. Finally, a full synthetic oil change.

I could be way over analyzing this. I'm not much of a mechanic, but I understand the basics.

Answer 1

Just drain all the old oil out and get a new filter and add the synthetic is all you have to do, DON'T mix regular oil with synthetic, you shouldn't have any problems whatsoever unless your car uses oil or leaks it as if it does it will use it or leak it a lot faster.

Answer 2

How can using synthetic oil do all you explain here???  People tend to make everything complicated.  Oil is oil, whetherr synthetic or regular mineral oil.  The only differencee is that synthetic oil lasts much longer, since it is more stable and takes longer to oxidize (break down).  As long as you use the right viscosity and change oil at the manufacturer's specified intervals, you should be good to go.

Oil cannot unseat pistons - never heard of it before now - who told you this?  On older engines, people sometimes use higher viscosity oil to reduce oil consumption, but that is not recommended by the manufacturers - I would stick to the specified oil (by the manufacturer), unless it REALLY uses (or burns) a LOT of oil - blue smoke whenever you pull away.

Answer 3

You can safely drain the old oil and replace the oil filter. Top up with the synthetic oil and she will run fine. There are no adverse effects while switching from conventional to synthetic oils. If this would have been the case, the manufacturers would have printed warnings on the oil containers.

Answer 4

You can safely switch back and forth from regular to synthetic oils.

The reason you sometimes hear about leakage problems following a switch to synthetic oils is that sludge build-up sometimes occurs inside engines and the detergents in synthetic oil helps clean out that sludge.  That can reveal previously covered dried out or deformed seals which results in an external leak or leaks.

Answer 5

All you do is a standard oil change. Synthetics and regular oil are fully compatible.

There is a long article available that was done by consumer reports that showed no benefit at all to using synthetic. It also showed no benefit to changing oil at 3,000 miles. It was a really interesting article. As a result, I switched back to the factory recommended oil change interval and just used the proper grade of oil for the season.

My Accord, which has since been sold to a friend, has over 300,000 miles on it without the engine ever having been opened except for routine maintenance. It is still running strong.

I guess what I am trying to say is that you can spend $10.00 per quart for Amsoil Synthetic and change every 3,000 miles, or just use whatever is on sale at Walmart and change it every 6,000 miles. Neither approach is better or worse than the other.

Look up the article and the methodology behind the study. It was good information.

They also tested various oil additives and found them to offer essentially no benefit at all.

Answer 6

"From what I understand, a simple switch from conventional motor oil to synthetic can cause a loss in power and it could unseat the piston seals."

"If I were to start by using one quart synthetic, 3 quarts conventional (the same brand, same weight) for an oil change."

On both counts, unfortunately you are wrong.

The first thing I am going to say is, whoever told you that changing oil could "unseat the piston seals" knows absolutely nothing about engines, please stop listening to their advice. The closest thing I could think of to what a 'piston seal' could possibly be would be the (compression) piston rings. These are never secured directly to the piston in the first place, they move inside the ring grooves and seal by spring tension against the cylinder, and contact against the sides of the ring grooves.

As far as "same brand, same weight", I can buy two 1 gallon plastic bottles of oil from the same company, that are both the same weight, they even look the same, but they are for COMPLETELY different purposes, and have widely different characteristics. When changing between mineral and synthetic oils, there is no need to do it in steps, you drain one, and fill up with the other (obviously changing filters at the same time, never re-use a filter element).

With regards to your engine, there is no good reason to change to synthetic oil now, you will notice no difference to fuel consumption, power, or quality of operation. If you want to waste money, go right ahead. If you don't, then keep using the standard oil until the car dies in another 100,000 miles.