gear box oil

[JamesHeath]

I have a betamarine 13.7hp diesel with a TMC 40 Gear box
The tmc manual says use only SAE 20/30 oil. I can't seem to find any The nearest I can get is SAE 20/50 As I understand it the numbers 20/30 Indicate the temperature range that the oil works ,so an 20/50 will work bettter at a higher temp. than 20/ 30 ??? Will the 20/ 50 be ok or are there other factors involved . I am hesitant to disregard what the manual say's

 

[sailorman]

phone Beta

 

[covenanter]

You only need to make sure lower number is correct 20.

 

[Refueler]

[ QUOTE ]
I have a betamarine 13.7hp diesel with a TMC 40 Gear box
The tmc manual says use only SAE 20/30 oil. I can't seem to find any The nearest I can get is SAE 20/50 As I understand it the numbers 20/30 Indicate the temperature range that the oil works ,so an 20/50 will work bettter at a higher temp. than 20/ 30 ??? Will the 20/ 50 be ok or are there other factors involved . I am hesitant to disregard what the manual say's

[/ QUOTE ]

No the numbers are Viscosity's and indicate the upper and lower "effective" viscosity of the oil. Temp. has a role to play of course and will dictate various factors that come into play.

 

[VicS]

As refueller says the numbers indicate the viscosity. the higher the number the higher the viscosity.

The double number indicates that it is a multigrade. A 20/50 oil has the same viscosity as a grade 20 oil when it is cold but that of a grade 50 oil when it is hot (I forget the temperatures that apply)
It does mean that when hot a 20/50 oil will be more viscous than a 20/30 oil but that does not mean it will be better, possibly not so good if the box is designed for a 20/30.
It is possible that a 15/40 oil would be a better choice especially if the box is not water cooled. Or a straight SAE30.

 

[PCUK]

Of course oils do not really get thicker (or more viscous) at higher temparatures, it is the protection factor that increases otherwise we wouldn't warm the engine before changing the oil. So any 20/* grade would do.

 

[Malish]

I would suggest you contact the manufacturer for clarification

After market" <colletti.mattia@technodrive.it>

They write good English!

 

[VicS]

[ QUOTE ]
Of course oils do not really get thicker (or more viscous) at higher temparatures

[/ QUOTE ] No they do not get thicker, they all get thinner but a multgrade oil does not thin as much as a single grade oil. So a 20/50 oil at 100C has the same viscosity as an SAE 50 oil at 100C. A 20/30 oil at 100C will only have the viscosity of an SAE 30 oil at 100C.

 

[Pye_End]

Are you sure?

I have the same combination and the Beta manual says ATF oil?

 

[Malish]

I didn't want to add the comment to my original answer for fear of causing confusion, but my TMC 40 M also takes ATF, hence the suggestion to e-mail Italy, including the gearbox serial number.

 

[Gaz22]

just changed mine ATF.and from the beta manual page 20.

Gearbox Lubricant Capacity (approx.)
TMC40 Use ATF Oil 0.20 litres