20w50 5W30 oil,not for use in a 4.9 liter engine?

[megatron]

I was wondering if its safe to use this weight of oil in my 94 deville? I'am in florida so woulden't 20w50 oil be to heavy here and could it damage my motor? The reason I ask is my friend who took my deville for an oil change for me while I was at work and when I asked her about it she just told they put either 20w50 or 5W30 oil in it!,I just about blew a gasket. I was like what the f**k? Now I'an no mehanic but isn't this oil weight bad for a car in the florida heat? I mean just cause I haven't heard of it dosen't mean its a bad thing but maybe they slacked off and just diddn't feel like ordering more oil. And figuring she was a girl and such just put that in,I can just have it changed out its not big thing but will it be ok? thanks.

[ACDC686]

Actually 20W50 might be pretty good during summer in FLA, but 5w30 is definately to to light, I use in winter it west-central Illinois. With 20W50 you should be good, maybe try 20W40 or if youre really paranoid use 10W30.

[megatron]

Ok iam almost sure 100% sure it was 20W50 she said that put in so if its ok then I'll just leave it in there.

[Stoneage_Caddy]

i run 15w40 Mobil Delvac in my 4.9 deville , if she loved you thats what she woulda had put in ...oviously shes plutonic LOL ...

the delvac is refered to by some as a "diesel engine oil"... what makes it great for a diesel makes it ideal for our 4.9s as we are more conerned with wear than we are about gas milage (by the way i get 21mpg and as high as 29), your valvetrain , oilpump and distrib gear will enjoy the delvac ...not to mention prolong the silent life of the number 1 main bearing

[megatron]

LOL yup stoneage shes plutonic although we've had fun on a couple of occasions :-) but decided to keep it ah-humm plutonic LOL we figured it better this was like friends with benifits :-). Anyways thanks for the reply as long as I know the oil won't hurt anything I'am happy.

[Stoneage_Caddy]

nope ..itll be just fine ...i aint had no problems and i live in tampa and run a heavier oil then you are ,so youll do just fine ....

now hopefully we can figure out that other mess you have

[Night Wolf]

I'm gonna keep running Mobil 1 synthetic extended performance 10W-30 until my 4.9 dies....... no main bearing thumb, no sludge or varnish build up at all, she stills lays rubber and runs like new 104k miles later

[daemart]

If you've ever been a Volkswagon mechanic (Bugs, I mean) then you probably heard or told people to never use a multi-grade oil. I myself don't like to rely on some chemical/heat reaction to determine the viscosity of the oil. I use straight 30W in all my cars- 96 Deville, 92 Deville, 90 Deville, 91 Century. You don't need a multi-grade oil here in Texas or in Florida either. I use straight 50W in my airplane, which is what's used in all single engine planes. GM wants you to use multi-grade just to cover their ass and besides who reads the owners manual about different viscosity in different parts of the country? By the way, 10W50 oil will never and I really mean never be 50W.