What is the proper procedure of going from synthetic oil back to regular? Is engine flush needed? My friend bought a used vehicle and prev owner used synthetic.

The vehicle has about 20k mi, it is a 2007 Hondah CR-V.

 

I have never made this switch, but when going the other way, all I have ever done is just have the engine oil drained normally. You certainly must have the filter changed when switching between oil types. If it makes you feel more comfortable, you could change the oil again after just another thousand miles or so, in order to get most of the rest of the synthetic out, but I never bothered with that.

 

Just do a regular oil change and don't worry about it, it's not going to affect anything.

 

thanks for comments guys

 

Out of curiosity, what's prompting his decision to go back to petroleum oil?

 

Agree with just do an oil and filter change. They 2 are compatible, for instance if you're on a road trip and have to top off -- of course, that's not ideal.

 

Probably wants to waste more natural resources, do more frequent oil changes, and reduce the life of the engine?

 

If it causes global warming and no more freezing temperatures ever in Dallas, I am all for it. Seriously.

 

Same here for NY..

 

Just so you know, the end result of gobal warming would be an ice age.

 

global warming actually causes climates to get colder.

 

I said that already.

 

Can't wait

 

.....you guys seem to have gotten a bit off-topic. I wanted to ask this exact question. Good thing i saw this thread.

I've used M1: EP Synthetic for the last 3 oil changes. It had 128K miles on it at the time.
The previous owner was using Castrol Synthetic blend.(the crappy one)

Since switching over to M1, i've developed a rear valve cover leak (which was fixed) and a TC cover leak that's been getting worse during the colder months.

I've been trying out Auto-RX, and i'm wrapping up my 1st rinse phase. (I was afraid of switching to Dino to do the Auto-RX)
Since Synthetic is prone to make leak problems look worse (seems like it was responsible for the leak in the 1st place); i was wondering if i can switch back to Dino oil with my next oil change and do a 2nd Auto-RX treatment.

Will it be okay to switch from Synthetic back to Dino? I've heard that it's not reccomended.

 

It is okay to switch back to dino. My car actually runs quieter with dino than with Mobil-1. Are you doing the Auto RX rinse phase with Mobil-1? I thought you are supposed to use dino for rinse phase.

 

Thanks for your reply. Yes, i'm done with the cleaning phase, and finishing the rinse phase. You're right, but it turns out it doesn't matter, unless you're engine is heavily sluged-up.

 

Dino causes seals to swell. Syn keeps them at their "normal" status. If you have a leak with syn, you have a problem that needs fixed.

Syn does not cause leaks. The reduction in seal swelling and the better cleaning properties of syn reveal (not cause) leaks. If you leak, you need a repair.

 

Not all dino causes seals to swell, and not all syn keeps them normal. It depends on the formulation and the seal in question.

That said, yes, the most syn will do is reveal problems that need to be fixed. It doesn't really start them per se. What I always hear is that some old engines have worn seals that are being plugged by deposits left by cheap dino oil; synthetics have superior cleaning properties and generally lower deposit formation, so they clean those deposits up and expose leaks.

I agree strongly that if such is the case, you should fix the problem no matter what oil you're using.

 

Am I doing what I was trying not to do? Perpetuating a myth?

At least I wasnt wrong in the cleaning properties part.

 

You were right about some cases. I just wanted to make the caveat because there are a lot of variables involved.

 

You can switch back/forth no problems. Your engine only has 20k on it.

 

Yes, it would be neglient for a major lubricant manufacturers to formulate a product that is incompatible with seals. The differing composition of seals presents problems that both petroleum oils and synthetics must overcome. As you state, ultimately it is the additive mix in oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.

 

^^ Can you elaborate or recommend me if I should stick with my AMSOIL 1 or go back dino for a few K miles? The reason is because I've just changed the valve cover and tube seals and was worried that the SYN fluid would hurt it?

Granted everything has cured and hopefully it was done right.

 

Synthetic oil shouldn't hurt anything. The only thing you'd want to do is to change your oil earlier than you normally would have, just to get any residue out of the system.

 

Jeff, are you also saying that if you had higher mileage that you couldn't do that? I have 109K and run dino just because that was what the car had in it at 90K when I bought it.

 

Try some maxlife in there. It has been known to recondition the seals.

 

You should be able to convert to synthetic oil with no problems. However, given you don't know the history of the vehicle for the 1st 90k miles, I would be inclined to run AutoRX through twice before making the switch.

This will minimize the risk of developing leaks later on, while cleaning the engine internals and ring packs.

See www.auto-rx.com and www.bobistheoilguy.com

 

OCD products ftw

 

Plus one!