Switching between Dino and synthetic oil.

[Rosco]

I was wondering if there are any negative results from switching back and forth between dino and synthetic oil for winter and summer operation.



For example, around November drain out the dino 15w40 and add Delvac1, Amsoil, or whatever synthetic 5w40 makes you happy. Then come April drain and refill with dino 15w40 again.



I know there use to be a rule of thumb that once you switched to synthetic oil you stayed with synthetic oil. Is this still true?

 

[klenger]

The synthetic has advantages year around. If you are going to switch, I'd do it year around. I don't think switching back and forth will do any harm though.

 

[amsoilman]

It certainly isn't the thing to do, as the additive packages are usualy different, at least the Amsoil additive package is not near the same as a conventional petrolium based engine oil. Why would you want to change back and forth anyway? Seems to me to leave the same type oil in the entire year, whether it's petrolium or synthetic.



Just my . 02 worth,



Wayne

amsoilman

 

[rbattelle]

Rosco,



I understand why you might want to switch back and forth, given the extraordinary cost for synthetics. For ordinary API-certified oils, there is absolutely no reason you cannot switch between synthetic and dino oil at will. I don't know about amsoil, since they are not API certified (as far as I know, someone will correct me if I'm wrong).

 

[Rosco]

The reason I posted this question is because it came up on another diesel truck website and it sparked my interest. Therefore, I figured asking here on the TDR wouldn't hurt since we have guys like amsoilman who are knowledgeable in this area.



I have one other question. Is it acceptable to run 5w40 synthetic year round or would 15w40 be a better choice in the summer.

 

[DCaswell]

I run 0w-40 year round, flows better at startup & you have 40 protection at operating temp. There is absolutely no ill effect switching from syn to reg product & back again each year. Some dealers in exotic lubes will tell you different but just not true

 

[COBRAJET]

rbattelle,



Just curious as to why the Amsoil dig in every one of your posts. Did you have an Amsoil related problem? Do you know someone who has? I do not know of anyone who has. I have not had a problem in over 1 million miles of use in personal vehicles. Amsoil does have API oils. None of the vehicles I have owned have said to put only an oil with the API symbol on them. They say to use an oil which conforms to API specs. Amsoil says it does... . right on the bottle... . it just has not paid for the certification. That doesn't mean it doesn't meet the certification. If it didn't I would think API or any one of the other oils who have the symbol would be all over Amsoil with lawsuits. I know of none. I have never had a dealer say not to use it. There sure are a lot of people using it on this site as well as on the other major "diesel boards". I have never seen one failure reported or one warranty denial for using Amsoil. I would be more critical of all the oils being sold as synthetics... which are not. Amsoil has a few of those as well... CJ

 

[Rosco]

Please don't turn this into an oil war. Too much blood has been spilled already.

 

[klenger]

Please don't turn this into an oil war. Too much blood has been spilled already.

... and Steve (Moderator) is in for surgery and told us not to burn the place down while he's out of commision.

 

[rbattelle]

I apologize, no oil war

Sorry, Cobrajet, I don't mean to dig Amsoil at all. Didn't know I was coming across that way. I think Amsoil makes a fine product. I know they do have some API-certified oil. It's just that in this case, we know that API certified means you can "mix-and-match", so to speak, but with Amsoils differing synthetic base stocks it might not be advisable.



I'm sorry if on other posts I've implied that Amsoil is sub-standard because it doesn't have an API certification. I just think it's important for people to know that in some cases. It was not my intention to offend anyone who uses Amsoil... it is a quality product.

 

[Hohn]

I can't see a problem with switch back and forth. I think it would be good way to help out the cold starts in winter. Modern synthetics don't have seal swell issues and such.



The once-synth-always-synth is a myth, IMHO. While the additive packages might not be the same, it's reasonable that there won't be any weird chem reactions causing sludge and such.



There are a lot of reasons to run synth year round. But it's clearly needed more in cold weather, while it's more of a luxury in warmer climates.



JMHO



\\Justin

 

[COBRAJET]

rbattelle,



Not looking for a war either. I was just curious if you had a failure using it. For the amount of money we all pay for our trucks we definitely get to have an opnion on what type of oil we use and why... just wondering what yours was... CJ

 

[JohnE]

back to original question



Rosco

I did the summer winter switch on conventional, but decided there must be a better way. I went to Amsoil 5W-30 and loved the winter performance, but in summer it just vented too much from the breather. I switched to 5W-40 Delvac1 2 years ago and will stay there. Best winter AND summer oil for me. Compliments the yearly change routine, too.



API certification requires more than just having them test the oil. It it also compliance with EPA permissable levels of certain additives that may degrade emission systems. AMSOIL uses zinc dithiophosphate (anti-wear additive) in higher levels than permited by API standards.



FWIW

I don't advise switching oil brands, either. The additive packages are similar, but do have some differences. I've scrapped a lot of sludge from pans on engines that got the "what's on sale" mix of oils.



edit

Many synthetic lubes were developed for severe duty and mostly HIGH temperature applications. Cold weather performance is a very nice added benefit.