10w40 and carbon build up??

[Carguy80]

i heard that 10w40 causes exessive carbon build up?is that really a truth?

and which one you put my 92 firebird,10w40 shell helix synthetic blend or castrol gtx5 lightec synthetic blend 10w40?which one would provide better protection and better cleaning to the engine?i would probaly choose 10w30,but they dont sell that in sweden

and one thing that i have wondering, pretty much all oils in europe are something like 5w40,10w40.10w50.and america 5w30 and 10w30.that is really strange

i calld last week mobil retailer in sweden and asked that do you have mobil oils in 5w30.he said something like maybe fullysynthetic but no dino or synthetic blends are not available.but if go and search american mobil oils in the internet,i can find all kind of different grades.and my owner manual says not to use 10w40.but they do sell here gm goodwrench dino oils 5w30 and 10w30.i have gm oils 5w30 in the engine right now,but i want to use synthetic blend oil because they have better cleaning additives and agents than dino oil,right?

 

[LarryL]

quote:

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i heard that 10w40 causes exessive carbon build up?is that really a truth?

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No, it's not true.

I assume that you have cold weather to deal with. Thinner oil is better. Look in the "Interesting Articles" section for the writings of Dr. A E Haas. I think his explination of viscosity will help guide you in your selection of oil. His advise might be a lot better than a salesperson in an auto parts store.

 

[widman]

The viscosity has nothing to do with carbon build up as long as it is not too thick to be cleand off the cylinder walls. It's the additive pack that keeps the engine clean.
Personally I prefer the cleanliness of the CI-4 diesel/gasoline oils, but they are harder to find in lower viscosities. In your climate a 10W-40 or 15W-40 might be a little too thick. Depending on the engine, I would probably stick with a 5W-40 or 5W-30.

 

[Carguy80]

i drive firebird 92 3.1 temperature where i drive here in sweden are about: +20f to +80f. (-7c.to+27c.)for now,im gonna stick with gm goodwrench 5w30 motor oil.but i think that i can get mobil clean 7500 5w30 somewhere.i can always try

 

[eljefino]

I think you're thinking of ring sticking from the old school 1980's dino 10w40s with tons of viscocity index improvers. They sheared and made quite a mess-- sometimes.

Modern 10w40s are much better; that Shell synth blend will probably be all right if you need/want that grade.

More effort is being spent on oils 10w30 and thinner. For example Phillips' 5w20, 5w30, and 10w30 have synthetics blended in while their thicker stuff, for sale for a similar price, has more dino and is "probably" more low-tech. So you should ask yourself which will protect better, today's Xw30 or yesterdays 10w40.

 

[Camu Mahubah]

I cannot believe 5w30 is not readily available in Sweden. What do Swedish use in their automobiles?

 

[Carguy80]

well,those oils that are easily available and oil brand that are sold here mostly,i think,are gm goodwrench 5w30 and 10w30 dyno oil.then there is a ac delco oils that i have been saw in these grades:15w40 dino,10w40,dino/blend and 20w50 dino.and then there is pennzoil,i have been seen those oils only one place,i think they sell that stuff in different places also but i have only seen that in car dealership near stockholm i think it was 10w40 synthetic blend.and 76 oils and wolfs head.castorl oils and shell helix oils.and grades what they use here are something like 0w30,0w40,5w40.fyllysynthetic and i think only synthetic blend grade is 10w40 and minelar oils are pretty much 10w40 and 15w40.and i think they all are pretty thick oils because temperature here in sweden is about maybe max 0f. (18c.) or littlebit colder and warm temperature during the summer about +80f. (+27c.) or little warmer sometimes but usually temperature is round the year +20f.to+80f.(-7c.to +27c.)so i think perfect grade would be just 5w30 or 10w30 year round.

 

[Carguy80]

if i use 10w40 synthetic blend shell helix or castrol gtx lightec,can it put too much stress to my oil pump or other engine parts?because last thing i want to do is NOT to damage my engine

 

[williar]

I agree, a 5w30 or 10w30 would be best, but a good 5w40 or even 10w40, preferably a synthetic or synthetic blend, would work well, too.

 

[eljefino]

You (probably) have a high pressure bypass that opens at some arbitrary high setting, 70 psi more or less. Your oil gets jammed through your pump, and if it's too cold/thick, simply dumps through the bypass back into the pan. This is more stress than your pump needs but except for extreme circumstances won't wear anything out.

Meanwhile the oil that's made it past the bypass is flowing more slowly than a thinner oil would. As it's after the bypass the two different weights are at the same pressure.

Do read aehass's writings on the subject.

An oil pressure gauge would help you find the grade that results in the approximate correct pressures both warm and cold: The spec is in your repair manual but 10psi per 1000 rpm warmed up is a rough lower estimate.

 

[Carguy80]

i think i try schaeffer synthetic blend supreme 5w30.should be best synthetic blend oil out there

i just wonder,how i can get that stuff in sweden,,,

 

[JohnBrowning]

Go with a good 5W40 synthetic or semi-synthetic.

 

[Carguy80]

where i live,there is no synthetic blend 5w40,only 10w40.

i could try fullysynthetic 5w40,but i dont never driven fullysynthetic before,so i dont want to take that chance,that it star to leak. i have 112500miles in my firebird.but i think i could get mobil blend 5w30 or 10w30 in sweden,maybe,,,