Last night I was changing the oil in the wife's rig & I put in one quart of 5W-30 along with the other 3.4 quarts of 5W-20. I thought about it after cursing myself out & decided to drain it out & refill with the correct & same 5W-20 weight oil. Would this have caused a problem if left with the mix matched oil weights? Did I do the right thing by draining it out? Was I being too damn anal could have left it alone without issue? Just want to know for it killed me to waste 4.4 quarts of good oil. Thanks.
I am not an expert on lubrication but I would have used the oil. I don't believe there is that much differance in the oils based on viscosity index. I don't think I would do it on a regular basis but if I need to add some oil I don't always have the same grade and brand each time. I hope we can get some other opinions on this.
I have been told by several late model car mechanics that you only want to run what is recommended as the tolerances in the newer motors are a lot tighter than they used to be. I always thought when you ran out of 30 wt., you could mix 1 quart of 10 wt and 1 quart of 20 wt. and get 2 quarts of 30 wt.
As long as the odd quart of oil was the same type,i.e. not synthetic thrown in with non-synthetic, you wouldn't have a problem.
actually, they say now that you CAN mix synthetic and nonsynthetic oils. as far as mixing weights, if it was something like 50 weight in a brand new car, i might be concerned.
That actually was part of the concern. I used 2 qts of Mobil 1 snyth. & two qts. of conventional oil.
I don't use synthetic, I don't care if we kill another dinosaur or not. They claim that you can mix the new stuff but I probably wouldn't. Just old and set in my ways I guess. I understand that you shouldn't run heavier oil than recommended in a late model mill, but I'm thinking that thinner oil shouldn't hurt. At least not a single quart in an oil change. its not like you're going to mix 1 qt of 10 weight and 3 qts of 30 weight and change it all to 10 weight. I normally run 20W40 in my truck in the summer ans 10w30 in the winter. But if I'm out on the hyway and have to buy a quart and they don't have the same weight I buy what I can and dump it in. I don't immediatly go and change my oil, A quart in 7 isn't going to effect much.
I have researched alot on synthetics and I use it in my dailey driver. Everything I have read says "do not mix syn with conventional".
In your case I would have changed it all out. But if it was all just oil it should not matter as all oils will blend when mixed together...the slight change in viscosity would not cause any problems...unless like was already said..putting a couple of quarts of 50 weight in a fresh engine with tight tolerances could cause some problems. I know a guy that was running a tired 6 cylinder with very loose clearance...he added a quart of power punch...a honey type oil additive. He felt the difference in the way the engine ran so at the next stop he needed another quart of oil so he added more power punch...same at the next stop....then the next stop was when his engine blew up...seems straight power punch in the crankcase was a little too thick for the pump to move! Its an extreme case but kinda the same idea.
You can mix Synthetics with Non-synthetics, hence Semi-synthetic oil you can buy, they don't do nothing special to mix it, but you are better off mixing it yourself, because you know how much ratio you get. I do it in my diesel all the time, it was actually recommended by my uncle(who is a very good and well known diesel mechanic). The regular oil doesn't drain as good as synthetic, which is better for engine start up. The synthetic lubes better, and dissipates water better.
Everything else being equal,mixing different weight oils just creates the average of the weights.Not a problem, unless the average is too thick.
My brother has a new Chysler 300 and the dealer told him the recommended oil is half conventional and half synthetic. They charge him over $40 for an oil change. I asked what the book recommended and he said he hasn't read it yet....... I'm glad I don't own it!
There are probably more "virgin",unread owner's manuals than any other type of autmobile related literature.Most people never even read the damn things.
Back when I was a kid changing oil at Dad's Texaco we had a drain rack in the wall that the round quart cans fit into upside down so the rest of the oil could drain out of the can. Everything went in there- trans fluid, Quaker State, Penzoil, Havoline all different weights. We sold it as "drippings" for 35 cents a quart. Had a customer that had us use that stuff in his Chrysler New Yorker every 3000 miles from brand new till over 150,000. Never had a problem. Had us replace the oil filter every other oil change too. I guess it was all new oil and he was diligent in the 3000 mile interval.
Here's a modern day version of that bottle rack your talking about. http://www.bob2000.com/ -Bigchief.
Thanks guys. A guess one lesson a learn was to have never kept this mishap my little secret and not have said a word to the wife. For you know any little thing that happened to the car from that point on would have been caused by the mis-matched oil in the engine. It was worth every penny to not hear the shit storm that could have resulted for this minor garage infraction.
Most of that is BS shoved at you by the manufacturers and the EPA. Those 0W10, 5W15, etc oils are strictly to get the CAFE to meet the Feds yearly rules. Ive run 20W50 for over 200K in my 94 Taurus and 94 Volvo. Most Taurus' are in the junkyard long before 200K. I also had a 95 Caprice ex cop car with the LT1 with over 300K on it. I know many using 10W30 and 20W50 on 2002-2005 cars and trucks in business/contractor use. These are driven hard and long and I'll wager they will show no measureable wear at 100K or more.
What happens exactly when you drain synthetic from an engine that has used it for say, a few years and replace it with the same weight and vicosity of the synthetic? Is that taboo?
When I worked as counter guy at an import parts store & repair shop we had a fella come in on a Saturday and buy a case of Castrol and 3 filters. As he was paying for it I looked out the window and saw smoke pouring out of his exhaust and some from under the hood. I asked him about. Seems on Wednesday he found he only had a quart of oil in the car so he added 3 more quarts.Trouble is he used 3 quarts of Wesson corn oil. Well, it made sense to him. Probably shouldn't have driven for 3 days that way. He came back 2 weeks later to have the mechanic look at it. 1 week later he came back to pick up his car with its newly rebuilt motor. I don't recommend the Wesson / synthetic / conventional mix.
Merc, I had a '85 Jetta that I ran to 375K using 20W-50 & changing it every 3K. Motor still ran strong, passed inspect, & fired up after only a brief hit of the key. It was the trans. that sent it to the junk yard!
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