• Guest, The rules for the P & N subforum have been updated to prohibit "ad hominem" or personal attacks against other posters. See the full details in the post "Politics and News Rules & Guidelines."

YACT: Oil

Xionide

Diamond Member
Apr 20, 2002
8,679
1
81
I bought a car and I will be doing an oil change and tune up this weekend. I do not know if it has synthetic in it or not. I called the napa guy and asked him what I should do and he said if I drain all the oil and then put synthetic in it it wouldnt hurt my engine but if I did it the other way around it would. I am planning to get as much of the old oil out as I can by running an extra court through to clean it out before I put the new oil in. I dont want to flush the engine with an oil flushing thing cause that may cause my engine to leak in other places. Is what the napa guy said correct? If there isnt synthetic in it and I put synthetic in will it hurt my engine?

-Xionide
 

Chiropteran

Diamond Member
Nov 14, 2003
9,811
110
106
A car engine is like a human body. If you cut back on the food a little it will lose weight and become more lean and efficient. I recommend running without oil for a few weeks.
 

Xionide

Diamond Member
Apr 20, 2002
8,679
1
81
Originally posted by: Chiropteran
A car engine is like a human body. If you cut back on the food a little it will lose weight and become more lean and efficient. I recommend running without oil for a few weeks.
I am a a bit of a car noob but I am not an idiot. (taps sarcastic meter)
 

Chiropteran

Diamond Member
Nov 14, 2003
9,811
110
106
I have heard about the same as you- if you go from regular to synthetic there shouldn't be a problem, it's when you switch from synthetic back to regular that cases problems. You should be fine.
 

Vette73

Lifer
Jul 5, 2000
21,505
8
0
Originally posted by: Don_Vito
Neither switch will harm anything. Synthetic and petroleum oil are fully compatible.

Correct.

Use a good 10W30 (or 5W30 if you live in alaska"i.e. very cold places")

I use Mobil1 in my parents Z28 and customers who plan on keeping their car more then 60K. And my old buick get Reg. Mobil 10W30

 

jteef

Golden Member
Feb 20, 2001
1,355
0
76
i just filled my m3 up with mobil 1 0w-40 syn. I think it runs smoother. The previous oil was dino.
 

GalvanizedYankee

Diamond Member
Oct 27, 2003
6,986
0
0
Xionide, I know nothing of the cars but did own an 83' RT100 BMW m/c, bought it with 80k on it and put 40k more on
before I sold it.

I put synthetic gear oil in the trans&diff when I first got it. It shifted so much better it was like a Suzuki :D
The dealer warned me of leakage a week after I did it, I laughed. In less than 5k I had weepy seals, oil on the rear wheel is a bad sign :(

I put regular gear oil in, ran it 1k, then drained it. I did that three times before everything dried up. Lesson learned !!

If your BMW car uses the same type of seals, that is from whoever BMW sources them from, BEWARE.

I say this because the engine could use the same type. I would check on a BMW forum for advice.

Normally synthetic is compatible w/dino, the two can be mixed if you like. Synthetics can sometimes find a false seal,
that is a place that would never leak with normal lube oils, but a synthetic finds the false seal and your car will be marking it's territory like a three legged stud dog :p

My bottom line would be to change oil often and just use a decent name brand. If you want to spend money use
Kendal (sp). When you pull the valve cover off, look for signs of light scuffing on the opening ramps of the cam.
If none is present, the engine has had a decent service life..


 

Balthazar

Golden Member
Apr 16, 2000
1,834
0
0
Originally posted by: Don_Vito
Neither switch will harm anything. Synthetic and petroleum oil are fully compatible.
You are correct sir.

Its funny how many people have been affected by the whole "Shouldnt switch." mentality. I wonder if the oil manuf.'s who dont have synthetic oil are to blame ;)
 

Balthazar

Golden Member
Apr 16, 2000
1,834
0
0
Originally posted by: galvanizedyankee
Xionide, I know nothing of the cars but did own an 83' RT100 BMW m/c, bought it with 80k on it and put 40k more on
before I sold it.

I put synthetic gear oil in the trans&diff when I first got it. It shifted so much better it was like a Suzuki :D
The dealer warned me of leakage a week after I did it, I laughed. In less than 5k I had weepy seals, oil on the rear wheel is a bad sign :(

I put regular gear oil in, ran it 1k, then drained it. I did that three times before everything dried up. Lesson learned !!

If your BMW car uses the same type of seals, that is from whoever BMW sources them from, BEWARE.

I say this because the engine could use the same type. I would check on a BMW forum for advice.

Normally synthetic is compatible w/dino, the two can be mixed if you like. Synthetics can sometimes find a false seal,
that is a place that would never leak with normal lube oils, but a synthetic finds the false seal and your car will be marking it's territory like a three legged stud dog :p

My bottom line would be to change oil often and just use a decent name brand. If you want to spend money use
Kendal (sp). When you pull the valve cover off, look for signs of light scuffing on the opening ramps of the cam.
If none is present, the engine has had a decent service life..
Your also reffering to an '83.

I could be wrong but synthetics werent exactly prevalent back then and I doubt manufacturers worried about the effects thereof.
Its highly possible that synthetic didnt mix well with the seals on that vehicle, but I cant remember the last time I heard somebody say that about a new (within 6 or 7 years) car.
 

AsianriceX

Golden Member
Dec 30, 2001
1,318
0
0
The main reason people find that synthetics leak after using normal dino oil is that the dino oil can crud up and cake up around leaky seals. The dino oil is only covering up a problem that should be fixed anyway. At least, that's my take on it.
 

TechnoKid

Diamond Member
Feb 12, 2001
5,575
0
0
Originally posted by: AsianriceX
The main reason people find that synthetics leak after using normal dino oil is that the dino oil can crud up and cake up around leaky seals. The dino oil is only covering up a problem that should be fixed anyway. At least, that's my take on it.
Synthetic oil also has better detergency and additive package; so if there was mess left behind by a dino oil, then the synthetic would clean that up and uncover all the leaks the the dino crud was preventing.

IMO, I find nothing wrong with switching between syn and dino; as long as your car doesn't have any leaks right now, it shouldn't leak when switching between the two. If your car is leaking or consuming with dino right now, it most likely leak even more with syn.

In any case, a syn is generally better than dino because of its better additive package, and syn's ability to withstand temperature and syn's shear stability over dino. Syn can also go longer drain intervals versus dino.

Go with a 10w30, it has less of a viscosity spread than 5w30, so it is more shear stable. Mobil 1 10w30 is a good syn. If you're BMW starts to consume some of the 10w30, then pour in about 1/2 qt of mobils 15w50; it will help slow consumption. Also, Mobil's 0w40 is a nice oil, but it does tend to shear down in viscosity towards a 30wt.
 

GalvanizedYankee

Diamond Member
Oct 27, 2003
6,986
0
0
Originally posted by: Balthazar
Originally posted by: galvanizedyankee
Xionide, I know nothing of the cars but did own an 83' RT100 BMW m/c, bought it with 80k on it and put 40k more on
before I sold it.

I put synthetic gear oil in the trans&diff when I first got it. It shifted so much better it was like a Suzuki :D
The dealer warned me of leakage a week after I did it, I laughed. In less than 5k I had weepy seals, oil on the rear wheel is a bad sign :(

I put regular gear oil in, ran it 1k, then drained it. I did that three times before everything dried up. Lesson learned !!

If your BMW car uses the same type of seals, that is from whoever BMW sources them from, BEWARE.

I say this because the engine could use the same type. I would check on a BMW forum for advice.

Normally synthetic is compatible w/dino, the two can be mixed if you like. Synthetics can sometimes find a false seal,
that is a place that would never leak with normal lube oils, but a synthetic finds the false seal and your car will be marking it's territory like a three legged stud dog :p

My bottom line would be to change oil often and just use a decent name brand. If you want to spend money use
Kendal (sp). When you pull the valve cover off, look for signs of light scuffing on the opening ramps of the cam.
If none is present, the engine has had a decent service life..
Your also reffering to an '83.

I could be wrong but synthetics werent exactly prevalent back then and I doubt manufacturers worried about the effects thereof.
Its highly possible that synthetic didnt mix well with the seals on that vehicle, but I cant remember the last time I heard somebody say that about a new (within 6 or 7 years) car.


Yes!! I am refering to my 83' BMW motorcycle.

Xionide is asking about an 84' 318i. So according to the math, thats 20 years. Git the point Balthazar :disgust:

Read the thread Xionide linked to get a FULL knowledge of his situation.

I sincerly doubt that the engine has had all seals and gaskets up-dated. Off hand I can't remember the name, it starts with the letter "V". The seals for synthetic that I've seen are light to bright blue in color.
 

Evadman

Administrator Emeritus<br>Elite Member
Feb 18, 2001
30,990
5
81
Originally posted by: LAUST
Originally posted by: CraigRT
I use Mobil1 10w in my car, and it's fantastic...
What does it do for you over Dino?
He goes faster by a tenth in the quarter because of weight savings. His wallet is $20 lighter.
 

KokomoGST

Diamond Member
Nov 13, 2001
3,758
0
0
In newer cars esp there shouldn't be any problems in switching between.

An older car (early 80s) may have the condition where the synthetic detergents and additives would dissolve deposits that were helping to seal the engine (the afforementioned "false seal"). But then if that's happening, you'll prolly have had to rebuild the engine in the future anywho. Amazing how good machining got over the years...
 

OS

Lifer
Oct 11, 1999
15,582
1
76
Originally posted by: Evadman

He goes faster by a tenth in the quarter because of weight savings. His wallet is $20 lighter.
He must have been carrying $20 in pennies then. :p

I actually shed 3/10ths with 3 lb lighter wheels all around and pulling out the intake resonator. Trapped 2.5 mph higher also.
 

flyfish

Senior member
Oct 23, 2000
856
0
0
I just switched from Mobile 1 to Rotella T Synth.
M1 is very good stuff, I just could not justify the price.
 

LAUST

Diamond Member
Sep 13, 2000
8,957
1
81
Originally posted by: Evadman
Originally posted by: LAUST
Originally posted by: CraigRT
I use Mobil1 10w in my car, and it's fantastic...
What does it do for you over Dino?
He goes faster by a tenth in the quarter because of weight savings. His wallet is $20 lighter.
LOL :beer:

I myself, I'd rather save the $3 a qt and hope my engine would go out at 100K miles.. if I can save $3 X 6qt X 8years of changes = almost $600, I can get a new 5.3 longblock for $800... It would be worth the $200 along with my savings to get a fresh block every 8 years. I remember when I rebuilt my block (unleaded conversion) on my 69.. wow fresh engines are so nice.

But alas... even with Dino and my blower my compression tests are always great :( ;)
 

TechnoKid

Diamond Member
Feb 12, 2001
5,575
0
0
Originally posted by: flyfish
I just switched from Mobile 1 to Rotella T Synth.
M1 is very good stuff, I just could not justify the price.
Shell Rotella T Synthetic is good stuff. Around me I can get it in 5w40 by the gallon for $12.93.

As for Mobil 1, I can get that in 5w30,10w30, or 15w30 for as low as $3.38 per quart.
 

Lithium381

Lifer
May 12, 2001
12,464
2
0
you'd be fine with dino oil......i've got an oil leak, it'd leak more with synthetic cause apparently it's thinner, that and it'd be more expensive! I change my oil about once every 4 months, depends on how much i drive, less over summer
 

Zee

Diamond Member
Nov 27, 1999
5,171
3
76
when you buy mobile1, keep in mind it comes in dino and synth form. Look at what you are buying
 

Eli

Super Moderator | Elite Member
Super Moderator
Oct 9, 1999
50,425
6
81
Originally posted by: Lithium381
you'd be fine with dino oil......i've got an oil leak, it'd leak more with synthetic cause apparently it's thinner, that and it'd be more expensive! I change my oil about once every 4 months, depends on how much i drive, less over summer
It's not thinner... viscosity is viscosity.

A 10W-30 synthetic and a 10W-30 conventional oil should have the same viscosity at operating temperature. The difference is that synthetic oils' molecules are all uniform. It doesen't contain any of the impurities, ie: large molecules like waxes and other things that are naturally found in conventional oil. That's what causes conventional oil to resist flow so much in colder temps.

On the other side of things, this also gives the oil much better high-temperature stability. Synthetic oil doesen't boil off like conventional oil does, changing its viscosity.

And finally, yes.. synthetic oil generally has a more robust additive package to begin with, so you get better detergency, friction reduction and wear protection. That's why you can theoretically run synthetic oils longer than conventional, as long as certain requirements are met.

First, your air filter can't suck. Yes, K&N air filters suck. They flow well, but due to the laws of physics, that also means they flow more dirt.

Second, your oil filter can't be a POS. It is your oil filter's job to catch anything that gets past the air filter(which will eventually make it into your oil..), PLUS helping to remove contamination caused by the engine itself.

Third, you can't guess. There are just too many variables. The only way to accurately judge the state of your oil is through oil analysis.

Modern conventional oils are excellent lubricants. Therefor, I recommend buying whatever oil you want. Buy the cheapest if you want. Spend the extra money on a quality air filter and oil filter. Afterall, even the best oil on the planet is rendered useless if there are solid particles in it.

Follow your manuals oil change interval recommendations. I think for many new cars, it is generally 3750 miles for Severe Service and 5000 miles for normal use. Believe it or not, most driving would be considered severe service. City driving, stop and go highway driving, light-to-light racing, long, steep inclines requiring a downshift, leadfoot, extreme heat, extreme cold, extreme dust, etc....

If your engine experiences any one or a combination of those things, you can't really change your oil "too much".. lol
 

ASK THE COMMUNITY